diff --git a/README.md b/README.md
index ff01688..31439a8 100644
--- a/README.md
+++ b/README.md
@@ -4,11 +4,11 @@ pyTMHMM is a Python 3.5+ implementation of the transmembrane helix predictor usi
 hidden Markov model ([TMHMM](http://www.cbs.dtu.dk/services/TMHMM/)) originally
 described in:
 
-E\. L.L. Sonnhammer, G. von Heijne, and A. Krogh. **A hidden Markov model for
+E.L. Sonnhammer, G. von Heijne, and A. Krogh. **A hidden Markov model for
 predicting transmembrane helices in protein sequences**. In J. Glasgow,
 T. Littlejohn, F. Major, R. Lathrop, D. Sankoff, and C. Sensen, editors,
 Proceedings of the Sixth International Conference on Intelligent Systems for
-Molecular Biology, pages 175-182, Menlo Park, CA, 1998. AAAI Press.
+Molecular Biology, pages 175-182, Menlo Park, CA, 1998. AAAI Press. PMID [9783223](https://pubmed.ncbi.nlm.nih.gov/9783223/)
 
 # Why?