diff --git a/src/Catalogue/Book.php b/src/Catalogue/Book.php
index 3785242..f2ddd7e 100644
--- a/src/Catalogue/Book.php
+++ b/src/Catalogue/Book.php
@@ -4,38 +4,14 @@
 
 namespace Akondas\Library\Catalogue;
 
-class Book
+final readonly class Book
 {
-    private ISBN $isbn;
-
-    private Title $title;
-
-    private Author $author;
-
-    private function __construct(ISBN $isbn, Title $title, Author $author)
+    private function __construct(public ISBN $isbn, public Title $title, public Author $author)
     {
-        $this->isbn = $isbn;
-        $this->title = $title;
-        $this->author = $author;
     }
 
     public static function of(string $isbn, string $title, string $author): self
     {
         return new self(new ISBN($isbn), new Title($title), new Author($author));
     }
-
-    public function bookIsbn(): ISBN
-    {
-        return $this->isbn;
-    }
-
-    public function title(): Title
-    {
-        return $this->title;
-    }
-
-    public function author(): Author
-    {
-        return $this->author;
-    }
 }
diff --git a/src/Catalogue/BookId.php b/src/Catalogue/BookId.php
index a46ffd8..6bfe05f 100644
--- a/src/Catalogue/BookId.php
+++ b/src/Catalogue/BookId.php
@@ -6,17 +6,14 @@
 
 use Akondas\Library\Common\UUID;
 
-final class BookId
+final readonly class BookId
 {
-    private UUID $bookId;
-
-    public function __construct(UUID $bookId)
+    public function __construct(public UUID $bookId)
     {
-        $this->bookId = $bookId;
     }
 
-    public function bookId(): UUID
+    public static function random(): self
     {
-        return $this->bookId;
+        return new self(UUID::random());
     }
 }
diff --git a/src/Catalogue/BookInstance.php b/src/Catalogue/BookInstance.php
index 4ee073a..39907a4 100644
--- a/src/Catalogue/BookInstance.php
+++ b/src/Catalogue/BookInstance.php
@@ -4,40 +4,14 @@
 
 namespace Akondas\Library\Catalogue;
 
-use Akondas\Library\Common\UUID;
-
-class BookInstance
+final readonly class BookInstance
 {
-    private ISBN $isbn;
-
-    private BookId $bookId;
-
-    private BookType $bookType;
-
-    private function __construct(ISBN $isbn, BookId $bookId, BookType $bookType)
+    private function __construct(public ISBN $isbn, public BookId $bookId, public BookType $bookType)
     {
-        $this->isbn = $isbn;
-        $this->bookId = $bookId;
-        $this->bookType = $bookType;
     }
 
     public static function of(Book $book, BookType $bookType): self
     {
-        return new self($book->bookIsbn(), new BookId(UUID::random()), $bookType);
-    }
-
-    public function bookIsbn(): ISBN
-    {
-        return $this->isbn;
-    }
-
-    public function bookId(): BookId
-    {
-        return $this->bookId;
-    }
-
-    public function bookType(): BookType
-    {
-        return $this->bookType;
+        return new self($book->isbn, BookId::random(), $bookType);
     }
 }
diff --git a/src/Catalogue/BookInstanceAddedToCatalogue.php b/src/Catalogue/BookInstanceAddedToCatalogue.php
index 818e84d..887bba2 100644
--- a/src/Catalogue/BookInstanceAddedToCatalogue.php
+++ b/src/Catalogue/BookInstanceAddedToCatalogue.php
@@ -7,34 +7,24 @@
 use Akondas\Library\Common\Event\DomainEvent;
 use Akondas\Library\Common\UUID;
 
-class BookInstanceAddedToCatalogue implements DomainEvent
+final readonly class BookInstanceAddedToCatalogue implements DomainEvent
 {
-    private UUID $eventId;
-
-    private string $isbn;
-
-    private BookType $bookType;
-
-    private UUID $bookId;
-
-    private \DateTimeImmutable $when;
-
-    private function __construct(UUID $eventId, string $isbn, BookType $bookType, UUID $bookId, \DateTimeImmutable $when)
-    {
-        $this->eventId = $eventId;
-        $this->isbn = $isbn;
-        $this->bookType = $bookType;
-        $this->bookId = $bookId;
-        $this->when = $when;
+    private function __construct(
+        public UUID $eventId,
+        public string $isbn,
+        public BookType $bookType,
+        public UUID $bookId,
+        public \DateTimeImmutable $when
+    ) {
     }
 
     public static function now(BookInstance $bookInstance): self
     {
         return new self(
             UUID::random(),
-            $bookInstance->bookIsbn()->isbn(),
-            $bookInstance->bookType(),
-            $bookInstance->bookId()->bookId(),
+            $bookInstance->isbn->isbn,
+            $bookInstance->bookType,
+            $bookInstance->bookId->bookId,
             new \DateTimeImmutable()
         );
     }
@@ -49,21 +39,6 @@ public function aggregateId(): UUID
         return $this->bookId;
     }
 
-    public function isbn(): string
-    {
-        return $this->isbn;
-    }
-
-    public function bookType(): BookType
-    {
-        return $this->bookType;
-    }
-
-    public function bookId(): UUID
-    {
-        return $this->bookId;
-    }
-
     public function when(): \DateTimeImmutable
     {
         return $this->when;
diff --git a/src/Catalogue/Catalogue.php b/src/Catalogue/Catalogue.php
index 6788455..d500c2d 100644
--- a/src/Catalogue/Catalogue.php
+++ b/src/Catalogue/Catalogue.php
@@ -9,15 +9,10 @@
 use Munus\Control\Option;
 use Munus\Control\TryTo;
 
-class Catalogue
+final readonly class Catalogue
 {
-    private CatalogueDatabase $database;
-    private DomainEventPublisher $eventPublisher;
-
-    public function __construct(CatalogueDatabase $database, DomainEventPublisher $eventPublisher)
+    public function __construct(private CatalogueDatabase $database, private DomainEventPublisher $eventPublisher)
     {
-        $this->database = $database;
-        $this->eventPublisher = $eventPublisher;
     }
 
     /**
diff --git a/src/Catalogue/ISBN.php b/src/Catalogue/ISBN.php
index 0313152..3ff9174 100644
--- a/src/Catalogue/ISBN.php
+++ b/src/Catalogue/ISBN.php
@@ -6,21 +6,12 @@
 
 use Isbn\Isbn as IsbnCode;
 
-class ISBN
+final readonly class ISBN
 {
-    private string $isbn;
-
-    public function __construct(string $isbn)
+    public function __construct(public string $isbn)
     {
         if (!(new IsbnCode())->validation->isbn($isbn)) {
             throw new \InvalidArgumentException('Invalid ISBN');
         }
-
-        $this->isbn = $isbn;
-    }
-
-    public function isbn(): string
-    {
-        return $this->isbn;
     }
 }
diff --git a/src/Catalogue/Title.php b/src/Catalogue/Title.php
index ea05ff7..da29adc 100644
--- a/src/Catalogue/Title.php
+++ b/src/Catalogue/Title.php
@@ -4,21 +4,12 @@
 
 namespace Akondas\Library\Catalogue;
 
-class Title
+final readonly class Title
 {
-    private string $title;
-
-    public function __construct(string $title)
+    public function __construct(public string $title)
     {
         if ($title === '') {
             throw new \InvalidArgumentException('Title cannot be empty');
         }
-
-        $this->title = $title;
-    }
-
-    public function title(): string
-    {
-        return $this->title;
     }
 }
diff --git a/src/Lending/Book/Domain/AvailableBook.php b/src/Lending/Book/Domain/AvailableBook.php
index 378af68..613db92 100644
--- a/src/Lending/Book/Domain/AvailableBook.php
+++ b/src/Lending/Book/Domain/AvailableBook.php
@@ -9,19 +9,14 @@
 use Akondas\Library\Common\Aggregate\Version;
 use Akondas\Library\Lending\LibraryBranch\Domain\LibraryBranchId;
 
-final class AvailableBook implements Book
+final readonly class AvailableBook implements Book
 {
-    private BookId $bookId;
-    private BookType $bookType;
-    private LibraryBranchId $libraryBranch;
-    private Version $version;
-
-    public function __construct(BookId $bookId, BookType $bookType, LibraryBranchId $libraryBranch, Version $version)
+    public function __construct(
+        public BookId $bookId,
+        public BookType $bookType,
+        public LibraryBranchId $libraryBranch,
+        public Version $version)
     {
-        $this->bookId = $bookId;
-        $this->bookType = $bookType;
-        $this->libraryBranch = $libraryBranch;
-        $this->version = $version;
     }
 
     public function bookId(): BookId
@@ -39,11 +34,6 @@ public function version(): Version
         return $this->version;
     }
 
-    public function libraryBranch(): LibraryBranchId
-    {
-        return $this->libraryBranch;
-    }
-
     public function isRestricted(): bool
     {
         return $this->bookType === BookType::RESTRICTED;
diff --git a/src/Lending/Book/Domain/BookOnHold.php b/src/Lending/Book/Domain/BookOnHold.php
index 429dbef..09e8905 100644
--- a/src/Lending/Book/Domain/BookOnHold.php
+++ b/src/Lending/Book/Domain/BookOnHold.php
@@ -10,41 +10,21 @@
 use Akondas\Library\Lending\LibraryBranch\Domain\LibraryBranchId;
 use Akondas\Library\Lending\Patron\Domain\PatronId;
 
-final class BookOnHold implements Book
+final readonly class BookOnHold implements Book
 {
-    private BookId $bookId;
-
-    private BookType $bookType;
-
-    private LibraryBranchId $libraryBranch;
-
-    private PatronId $byPatron;
-
-    private \DateTimeImmutable $holdTill;
-
-    private Version $version;
-
-    /**
-     * BookOnHold constructor.
-     */
-    public function __construct(BookId $bookId, BookType $bookType, LibraryBranchId $libraryBranch, PatronId $byPatron, \DateTimeImmutable $holdTill, Version $version)
+    public function __construct(
+        public BookId $bookId,
+        public BookType $bookType,
+        public LibraryBranchId $libraryBranch,
+        public PatronId $byPatron,
+        public \DateTimeImmutable $holdTill,
+        public Version $version)
     {
-        $this->bookId = $bookId;
-        $this->bookType = $bookType;
-        $this->libraryBranch = $libraryBranch;
-        $this->byPatron = $byPatron;
-        $this->holdTill = $holdTill;
-        $this->version = $version;
     }
 
     public function by(PatronId $patronId): bool
     {
-        return $this->byPatron->patronId()->isEqual($patronId->patronId());
-    }
-
-    public function libraryBranch(): LibraryBranchId
-    {
-        return $this->libraryBranch;
+        return $this->byPatron->patronId->isEqual($patronId->patronId);
     }
 
     public function bookId(): BookId
@@ -61,14 +41,4 @@ public function version(): Version
     {
         return $this->version;
     }
-
-    public function byPatron(): PatronId
-    {
-        return $this->byPatron;
-    }
-
-    public function holdTill(): \DateTimeImmutable
-    {
-        return $this->holdTill;
-    }
 }
diff --git a/src/Lending/LibraryBranch/Domain/LibraryBranchId.php b/src/Lending/LibraryBranch/Domain/LibraryBranchId.php
index 6304ebd..b450281 100644
--- a/src/Lending/LibraryBranch/Domain/LibraryBranchId.php
+++ b/src/Lending/LibraryBranch/Domain/LibraryBranchId.php
@@ -6,17 +6,9 @@
 
 use Akondas\Library\Common\UUID;
 
-final class LibraryBranchId
+final readonly class LibraryBranchId
 {
-    private UUID $libraryBranchId;
-
-    public function __construct(UUID $libraryBranchId)
-    {
-        $this->libraryBranchId = $libraryBranchId;
-    }
-
-    public function libraryBranchId(): UUID
+    public function __construct(public UUID $libraryBranchId)
     {
-        return $this->libraryBranchId;
     }
 }
diff --git a/src/Lending/Patron/Domain/Hold.php b/src/Lending/Patron/Domain/Hold.php
index 16fac14..615271c 100644
--- a/src/Lending/Patron/Domain/Hold.php
+++ b/src/Lending/Patron/Domain/Hold.php
@@ -7,24 +7,9 @@
 use Akondas\Library\Catalogue\BookId;
 use Akondas\Library\Lending\LibraryBranch\Domain\LibraryBranchId;
 
-class Hold
+final readonly class Hold
 {
-    private BookId $bookId;
-    private LibraryBranchId $libraryBranchId;
-
-    public function __construct(BookId $bookId, LibraryBranchId $libraryBranchId)
-    {
-        $this->bookId = $bookId;
-        $this->libraryBranchId = $libraryBranchId;
-    }
-
-    public function bookId(): BookId
-    {
-        return $this->bookId;
-    }
-
-    public function libraryBranchId(): LibraryBranchId
+    public function __construct(public BookId $bookId, public LibraryBranchId $libraryBranchId)
     {
-        return $this->libraryBranchId;
     }
 }
diff --git a/src/Lending/Patron/Domain/HoldDuration.php b/src/Lending/Patron/Domain/HoldDuration.php
index 6126a5d..681dcb6 100644
--- a/src/Lending/Patron/Domain/HoldDuration.php
+++ b/src/Lending/Patron/Domain/HoldDuration.php
@@ -4,20 +4,13 @@
 
 namespace Akondas\Library\Lending\Patron\Domain;
 
-use Munus\Control\Option;
-
-final class HoldDuration
+final readonly class HoldDuration
 {
-    private \DateTimeImmutable $from;
-    private ?\DateTimeImmutable $to;
-
-    private function __construct(\DateTimeImmutable $from, ?\DateTimeImmutable $to)
+    private function __construct(public \DateTimeImmutable $from, public ?\DateTimeImmutable $to)
     {
         if ($to !== null && $to < $from) {
             throw new \InvalidArgumentException('Close-ended duration must be valid');
         }
-        $this->from = $from;
-        $this->to = $to;
     }
 
     public static function openEnded(): self
@@ -29,20 +22,7 @@ public static function closeEnded(NumberOfDays $days): self
     {
         $now = new \DateTimeImmutable();
 
-        return new self($now, $now->modify(sprintf('+%s days', $days->days())));
-    }
-
-    public function from(): \DateTimeImmutable
-    {
-        return $this->from;
-    }
-
-    /**
-     * @return Option<\DateTimeImmutable>
-     */
-    public function to(): Option
-    {
-        return Option::of($this->to);
+        return new self($now, $now->modify(sprintf('+%s days', $days->days)));
     }
 
     public function isOpenEnded(): bool
diff --git a/src/Lending/Patron/Domain/NumberOfDays.php b/src/Lending/Patron/Domain/NumberOfDays.php
index fa7a195..c296691 100644
--- a/src/Lending/Patron/Domain/NumberOfDays.php
+++ b/src/Lending/Patron/Domain/NumberOfDays.php
@@ -4,16 +4,13 @@
 
 namespace Akondas\Library\Lending\Patron\Domain;
 
-final class NumberOfDays
+final readonly class NumberOfDays
 {
-    private int $days;
-
-    private function __construct(int $days)
+    private function __construct(public int $days)
     {
         if ($days <= 0) {
             throw new \InvalidArgumentException('Cannot use negative integer or zero as number of days');
         }
-        $this->days = $days;
     }
 
     public static function of(int $days): self
@@ -21,11 +18,6 @@ public static function of(int $days): self
         return new self($days);
     }
 
-    public function days(): int
-    {
-        return $this->days;
-    }
-
     public function isGreaterThan(int $days): bool
     {
         return $this->days > $days;
diff --git a/src/Lending/Patron/Domain/Patron.php b/src/Lending/Patron/Domain/Patron.php
index 067f4d7..d203a01 100644
--- a/src/Lending/Patron/Domain/Patron.php
+++ b/src/Lending/Patron/Domain/Patron.php
@@ -12,25 +12,13 @@
 use Munus\Control\Either;
 use Munus\Control\Option;
 
-final class Patron
+final readonly class Patron
 {
-    private PatronInformation $patron;
-
-    /**
-     * @var GenericList<covariant PlacingOnHoldPolicy>
-     */
-    private GenericList $placingOnHoldPolicies;
-
-    private PatronHolds $patronHolds;
-
     /**
      * @param GenericList<covariant PlacingOnHoldPolicy> $placingOnHoldPolicies
      */
-    public function __construct(PatronInformation $patron, GenericList $placingOnHoldPolicies, PatronHolds $patronHolds)
+    public function __construct(public PatronInformation $patron, public GenericList $placingOnHoldPolicies, public PatronHolds $patronHolds)
     {
-        $this->patron = $patron;
-        $this->placingOnHoldPolicies = $placingOnHoldPolicies;
-        $this->patronHolds = $patronHolds;
     }
 
     public function isRegular(): bool
@@ -45,10 +33,10 @@ public function placeOnHold(AvailableBook $aBook, HoldDuration $holdDuration): E
     {
         $rejection = $this->patronCanHold($aBook, $holdDuration);
         if ($rejection->isEmpty()) {
-            return Either::right(BookPlacedOnHold::now($this->patron->patronId(), $aBook->bookId(), $aBook->bookType(), $aBook->libraryBranch(), $holdDuration));
+            return Either::right(BookPlacedOnHold::now($this->patron->patronId, $aBook->bookId(), $aBook->bookType(), $aBook->libraryBranch, $holdDuration));
         }
 
-        return Either::left(BookHoldFailed::now($this->patron->patronId(), $rejection->get()->reason(), $aBook->bookId(), $aBook->libraryBranch(), $holdDuration));
+        return Either::left(BookHoldFailed::now($this->patron->patronId, $rejection->get()->reason, $aBook->bookId(), $aBook->libraryBranch, $holdDuration));
     }
 
     public function numberOfHolds(): int
diff --git a/src/Lending/Patron/Domain/PatronEvent/BookHoldFailed.php b/src/Lending/Patron/Domain/PatronEvent/BookHoldFailed.php
index 88ae954..0c90158 100644
--- a/src/Lending/Patron/Domain/PatronEvent/BookHoldFailed.php
+++ b/src/Lending/Patron/Domain/PatronEvent/BookHoldFailed.php
@@ -11,27 +11,18 @@
 use Akondas\Library\Lending\Patron\Domain\PatronEvent;
 use Akondas\Library\Lending\Patron\Domain\PatronId;
 
-final class BookHoldFailed implements PatronEvent
+final readonly class BookHoldFailed implements PatronEvent
 {
-    private UUID $eventId;
-    private PatronId $patronId;
-    private string $reason;
-    private BookId $bookId;
-    private LibraryBranchId $libraryBranchId;
-    private \DateTimeImmutable $when;
-    private \DateTimeImmutable $holdFrom;
-    private ?\DateTimeImmutable $holdTill;
-
-    public function __construct(UUID $eventId, PatronId $patronId, string $reason, BookId $bookId, LibraryBranchId $libraryBranchId, \DateTimeImmutable $when, \DateTimeImmutable $holdFrom, ?\DateTimeImmutable $holdTill)
+    public function __construct(
+        public UUID $eventId,
+        public PatronId $patronId,
+        public string $reason,
+        public BookId $bookId,
+        public LibraryBranchId $libraryBranchId,
+        public \DateTimeImmutable $when,
+        public \DateTimeImmutable $holdFrom,
+        public ?\DateTimeImmutable $holdTill)
     {
-        $this->eventId = $eventId;
-        $this->patronId = $patronId;
-        $this->reason = $reason;
-        $this->bookId = $bookId;
-        $this->libraryBranchId = $libraryBranchId;
-        $this->when = $when;
-        $this->holdFrom = $holdFrom;
-        $this->holdTill = $holdTill;
     }
 
     public static function now(PatronId $patronId, string $reason, BookId $bookId, LibraryBranchId $libraryBranchId, HoldDuration $holdDuration): self
@@ -43,8 +34,8 @@ public static function now(PatronId $patronId, string $reason, BookId $bookId, L
             $bookId,
             $libraryBranchId,
             new \DateTimeImmutable(),
-            $holdDuration->from(),
-            $holdDuration->to()->getOrNull()
+            $holdDuration->from,
+            $holdDuration->to
         );
     }
 
@@ -55,7 +46,7 @@ public function patronId(): PatronId
 
     public function aggregateId(): UUID
     {
-        return $this->patronId->patronId();
+        return $this->patronId->patronId;
     }
 
     public function eventId(): UUID
@@ -67,29 +58,4 @@ public function when(): \DateTimeImmutable
     {
         return $this->when;
     }
-
-    public function reason(): string
-    {
-        return $this->reason;
-    }
-
-    public function bookId(): BookId
-    {
-        return $this->bookId;
-    }
-
-    public function libraryBranchId(): LibraryBranchId
-    {
-        return $this->libraryBranchId;
-    }
-
-    public function holdFrom(): \DateTimeImmutable
-    {
-        return $this->holdFrom;
-    }
-
-    public function holdTill(): ?\DateTimeImmutable
-    {
-        return $this->holdTill;
-    }
 }
diff --git a/src/Lending/Patron/Domain/PatronEvent/BookPlacedOnHold.php b/src/Lending/Patron/Domain/PatronEvent/BookPlacedOnHold.php
index a57f64f..10500df 100644
--- a/src/Lending/Patron/Domain/PatronEvent/BookPlacedOnHold.php
+++ b/src/Lending/Patron/Domain/PatronEvent/BookPlacedOnHold.php
@@ -14,25 +14,16 @@
 
 final class BookPlacedOnHold implements PatronEvent
 {
-    private UUID $eventId;
-    private PatronId $patronId;
-    private BookId $bookId;
-    private BookType $bookType;
-    private LibraryBranchId $libraryBranchId;
-    private \DateTimeImmutable $holdFrom;
-    private ?\DateTimeImmutable $holdTill;
-    private \DateTimeImmutable $when;
-
-    private function __construct(UUID $eventId, PatronId $patronId, BookId $bookId, BookType $bookType, LibraryBranchId $libraryBranchId, \DateTimeImmutable $when, \DateTimeImmutable $holdFrom, ?\DateTimeImmutable $holdTill)
+    private function __construct(
+        public UUID $eventId,
+        public PatronId $patronId,
+        public BookId $bookId,
+        public BookType $bookType,
+        public LibraryBranchId $libraryBranchId,
+        public \DateTimeImmutable $when,
+        public \DateTimeImmutable $holdFrom,
+        public ?\DateTimeImmutable $holdTill)
     {
-        $this->eventId = $eventId;
-        $this->patronId = $patronId;
-        $this->bookId = $bookId;
-        $this->bookType = $bookType;
-        $this->libraryBranchId = $libraryBranchId;
-        $this->when = $when;
-        $this->holdFrom = $holdFrom;
-        $this->holdTill = $holdTill;
     }
 
     public static function now(PatronId $patronId, BookId $bookId, BookType $bookType, LibraryBranchId $libraryBranchId, HoldDuration $holdDuration): self
@@ -44,26 +35,11 @@ public static function now(PatronId $patronId, BookId $bookId, BookType $bookTyp
             $bookType,
             $libraryBranchId,
             new \DateTimeImmutable(),
-            $holdDuration->from(),
-            $holdDuration->to()->getOrNull()
+            $holdDuration->from,
+            $holdDuration->to
         );
     }
 
-    public function bookId(): BookId
-    {
-        return $this->bookId;
-    }
-
-    public function holdFrom(): \DateTimeImmutable
-    {
-        return $this->holdFrom;
-    }
-
-    public function holdTill(): ?\DateTimeImmutable
-    {
-        return $this->holdTill;
-    }
-
     public function patronId(): PatronId
     {
         return $this->patronId;
@@ -76,21 +52,11 @@ public function eventId(): UUID
 
     public function aggregateId(): UUID
     {
-        return $this->patronId->patronId();
+        return $this->patronId->patronId;
     }
 
     public function when(): \DateTimeImmutable
     {
         return $this->when;
     }
-
-    public function bookType(): BookType
-    {
-        return $this->bookType;
-    }
-
-    public function libraryBranchId(): LibraryBranchId
-    {
-        return $this->libraryBranchId;
-    }
 }
diff --git a/src/Lending/Patron/Domain/PatronHolds.php b/src/Lending/Patron/Domain/PatronHolds.php
index 148234c..1db1e87 100644
--- a/src/Lending/Patron/Domain/PatronHolds.php
+++ b/src/Lending/Patron/Domain/PatronHolds.php
@@ -8,26 +8,20 @@
 use Akondas\Library\Lending\Book\Domain\BookOnHold;
 use Munus\Collection\Set;
 
-class PatronHolds
+final readonly class PatronHolds
 {
-    public const MAX_NUMBER_OF_HOLDS = 5;
-
-    /**
-     * @var Set<Hold>
-     */
-    private Set $resourcesOnHold;
+    public const int MAX_NUMBER_OF_HOLDS = 5;
 
     /**
      * @param Set<Hold> $resourcesOnHold
      */
-    public function __construct(Set $resourcesOnHold)
+    public function __construct(public Set $resourcesOnHold)
     {
-        $this->resourcesOnHold = $resourcesOnHold;
     }
 
     public function a(BookOnHold $bookOnHold): bool
     {
-        return $this->resourcesOnHold->contains(new Hold($bookOnHold->bookId(), $bookOnHold->libraryBranch()));
+        return $this->resourcesOnHold->contains(new Hold($bookOnHold->bookId(), $bookOnHold->libraryBranch));
     }
 
     public function count(): int
diff --git a/src/Lending/Patron/Domain/PatronId.php b/src/Lending/Patron/Domain/PatronId.php
index f32c954..ea7be6f 100644
--- a/src/Lending/Patron/Domain/PatronId.php
+++ b/src/Lending/Patron/Domain/PatronId.php
@@ -6,17 +6,9 @@
 
 use Akondas\Library\Common\UUID;
 
-final class PatronId
+final readonly class PatronId
 {
-    private UUID $patronId;
-
-    public function __construct(UUID $patronId)
-    {
-        $this->patronId = $patronId;
-    }
-
-    public function patronId(): UUID
+    public function __construct(public UUID $patronId)
     {
-        return $this->patronId;
     }
 }
diff --git a/src/Lending/Patron/Domain/PatronInformation.php b/src/Lending/Patron/Domain/PatronInformation.php
index d7e70e7..8dcf14a 100644
--- a/src/Lending/Patron/Domain/PatronInformation.php
+++ b/src/Lending/Patron/Domain/PatronInformation.php
@@ -4,25 +4,10 @@
 
 namespace Akondas\Library\Lending\Patron\Domain;
 
-final class PatronInformation
+final readonly class PatronInformation
 {
-    private PatronId $patronId;
-    private PatronType $patronType;
-
-    public function __construct(PatronId $patronId, PatronType $patronType)
-    {
-        $this->patronId = $patronId;
-        $this->patronType = $patronType;
-    }
-
-    public function patronId(): PatronId
-    {
-        return $this->patronId;
-    }
-
-    public function patronType(): PatronType
+    public function __construct(public PatronId $patronId, public PatronType $patronType)
     {
-        return $this->patronType;
     }
 
     public function isRegular(): bool
diff --git a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanHoldRestrictedBooks.php b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanHoldRestrictedBooks.php
index cd5c7ba..a480108 100644
--- a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanHoldRestrictedBooks.php
+++ b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanHoldRestrictedBooks.php
@@ -10,7 +10,7 @@
 use Akondas\Library\Lending\Patron\Domain\PlacingOnHoldPolicy;
 use Munus\Control\Either;
 
-final class OnlyResearcherPatronsCanHoldRestrictedBooks implements PlacingOnHoldPolicy
+final readonly class OnlyResearcherPatronsCanHoldRestrictedBooks implements PlacingOnHoldPolicy
 {
     /**
      * @return Either<Rejection,Allowance>
diff --git a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanPlaceOpenEndedHolds.php b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanPlaceOpenEndedHolds.php
index 2d39ba7..41ef89a 100644
--- a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanPlaceOpenEndedHolds.php
+++ b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/OnlyResearcherPatronsCanPlaceOpenEndedHolds.php
@@ -12,7 +12,7 @@
 use Munus\Control\Either\Left;
 use Munus\Control\Either\Right;
 
-final class OnlyResearcherPatronsCanPlaceOpenEndedHolds implements PlacingOnHoldPolicy
+final readonly class OnlyResearcherPatronsCanPlaceOpenEndedHolds implements PlacingOnHoldPolicy
 {
     /**
      * @return Either<Rejection,Allowance>
diff --git a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/RegularPatronMaximumNumberOfHoldsPolicy.php b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/RegularPatronMaximumNumberOfHoldsPolicy.php
index f8cab1d..b54513f 100644
--- a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/RegularPatronMaximumNumberOfHoldsPolicy.php
+++ b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/RegularPatronMaximumNumberOfHoldsPolicy.php
@@ -13,7 +13,7 @@
 use Munus\Control\Either\Left;
 use Munus\Control\Either\Right;
 
-class RegularPatronMaximumNumberOfHoldsPolicy implements PlacingOnHoldPolicy
+final readonly class RegularPatronMaximumNumberOfHoldsPolicy implements PlacingOnHoldPolicy
 {
     public function __invoke(AvailableBook $toHold, Patron $patron, HoldDuration $holdDuration): Either
     {
diff --git a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/Rejection.php b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/Rejection.php
index 10fe925..f63b0aa 100644
--- a/src/Lending/Patron/Domain/PlacingOnHoldPolicy/Rejection.php
+++ b/src/Lending/Patron/Domain/PlacingOnHoldPolicy/Rejection.php
@@ -4,17 +4,9 @@
 
 namespace Akondas\Library\Lending\Patron\Domain\PlacingOnHoldPolicy;
 
-final class Rejection
+final readonly class Rejection
 {
-    private string $reason;
-
-    public function __construct(string $reason)
-    {
-        $this->reason = $reason;
-    }
-
-    public function reason(): string
+    public function __construct(public string $reason)
     {
-        return $this->reason;
     }
 }
diff --git a/tests/Context/DomainContext.php b/tests/Context/DomainContext.php
index 1daf5f8..4ef3ea2 100644
--- a/tests/Context/DomainContext.php
+++ b/tests/Context/DomainContext.php
@@ -41,7 +41,7 @@ public function aRegularPatronWithHoldsPlaceOnHold(int $holds, int $days): void
      */
     public function placeOnHoldShouldFailWithReason(string $reason): void
     {
-        assertTrue($this->hold && $this->hold->getLeft()->reason() === $reason);
+        assertTrue($this->hold && $this->hold->getLeft()->reason === $reason);
     }
 
     /**
diff --git a/tests/Fixture/BookFixture.php b/tests/Fixture/BookFixture.php
index 9a2a5ba..2b13b0a 100644
--- a/tests/Fixture/BookFixture.php
+++ b/tests/Fixture/BookFixture.php
@@ -30,7 +30,7 @@ function anyBranch(): LibraryBranchId
     return new LibraryBranchId(UUID::random());
 }
 
-define('DDD_ISBN_STR', (string) 9780321125217);
+const DDD_ISBN_STR = '9780321125217';
 
 function dddBook(): Book
 {
diff --git a/tests/Unit/Catalogue/CatalogueTest.php b/tests/Unit/Catalogue/CatalogueTest.php
index 5b39f57..5d903c9 100644
--- a/tests/Unit/Catalogue/CatalogueTest.php
+++ b/tests/Unit/Catalogue/CatalogueTest.php
@@ -4,6 +4,7 @@
 
 namespace Akondas\Library\Tests\Unit\Catalogue;
 
+use Akondas\Library\Catalogue\BookInstance;
 use Akondas\Library\Catalogue\BookInstanceAddedToCatalogue;
 use Akondas\Library\Catalogue\BookType;
 use Akondas\Library\Catalogue\Catalogue;
@@ -43,6 +44,8 @@ public function testGetBookFromCatalogue(): void
 
     public function testPutBookToCatalogue(): void
     {
+        // given
+        $this->database->method('saveBook')->willReturn(dddBook());
         // when
         $result = $this->catalogue->addBook(DDD_ISBN_STR, 'Domain Driven Design', 'Eric Evans');
         // then
@@ -59,6 +62,7 @@ public function testPutNewBookInstanceToCatalogue(): void
             ->expects(self::once())
             ->method('publish')
             ->with(self::isInstanceOf(BookInstanceAddedToCatalogue::class));
+        $this->database->method('saveBookInstance')->willReturn(BookInstance::of(dddBook(), BookType::RESTRICTED));
         // when
         $result = $this->catalogue->addBookInstance(DDD_ISBN_STR, BookType::RESTRICTED);
         // then
diff --git a/tests/Unit/Common/UUIDTest.php b/tests/Unit/Common/UUIDTest.php
index ea4746b..85a0ff1 100644
--- a/tests/Unit/Common/UUIDTest.php
+++ b/tests/Unit/Common/UUIDTest.php
@@ -5,9 +5,11 @@
 namespace Akondas\Library\Tests\Unit\Common;
 
 use Akondas\Library\Common\UUID;
+use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 
+#[CoversClass(UUID::class)]
 final class UUIDTest extends TestCase
 {
     #[Test]
diff --git a/tests/Unit/Lending/Patron/Domain/PatronRequestingOpenEndedHoldTest.php b/tests/Unit/Lending/Patron/Domain/PatronRequestingOpenEndedHoldTest.php
index 20a7a97..a265dc5 100644
--- a/tests/Unit/Lending/Patron/Domain/PatronRequestingOpenEndedHoldTest.php
+++ b/tests/Unit/Lending/Patron/Domain/PatronRequestingOpenEndedHoldTest.php
@@ -24,8 +24,8 @@ public function testResearcherPatronCanRequestCloseEndedHold(): void
         $event = $hold->get();
         self::assertInstanceOf(BookPlacedOnHold::class, $event);
         self::assertEquals($patronId, $event->patronId());
-        self::assertEquals($aBook->bookId(), $event->bookId());
-        self::assertNull($event->holdTill());
+        self::assertEquals($aBook->bookId(), $event->bookId);
+        self::assertNull($event->holdTill);
     }
 
     public function testRegularPatronCannotRequestOpenEndedHold(): void
@@ -36,7 +36,7 @@ public function testRegularPatronCannotRequestOpenEndedHold(): void
         self::assertTrue($hold->isLeft());
         self::assertStringContainsString(
             'Regular patron cannot place open ended holds',
-            $hold->getLeft()->reason()
+            $hold->getLeft()->reason
         );
     }
 }
diff --git a/tests/Unit/Lending/Patron/Domain/RegularPatronRequestingRestrictedBooksTest.php b/tests/Unit/Lending/Patron/Domain/RegularPatronRequestingRestrictedBooksTest.php
index fac5c78..2459fec 100644
--- a/tests/Unit/Lending/Patron/Domain/RegularPatronRequestingRestrictedBooksTest.php
+++ b/tests/Unit/Lending/Patron/Domain/RegularPatronRequestingRestrictedBooksTest.php
@@ -18,7 +18,7 @@ public function testARegularPatronCannotPlaceOnHoldRestrictedBook(): void
         self::assertTrue($hold->isLeft());
         self::assertStringContainsString(
             'Regular patrons cannot hold restricted books',
-            $hold->getLeft()->reason()
+            $hold->getLeft()->reason
         );
     }
 }