replace reference with their doi links

fixes #107

docs/_Research-Data-Management/13-data-qc.md

@@ -170,7 +170,7 @@ Legend:
 - **source**: Dim. reduction embedding, negative control study
 - **possible reason(s)**: use raw data for tSNE/UMAP
 - **solution/measure**: use a significant portion of PC from the PCA as input for tSNE/UMAP
-3. "The first two principle components were used to perform a tSNE" [https://www.science.org/doi/full/10.1126/science.aag3009](https://www.science.org/doi/full/10.1126/science.aag3009)
+3. "The first two principle components were used to perform a tSNE" <https://doi.org/10.1126/science.aag3009>
 - **source**: Dim. reduction embedding, negative control study
 - **possible reason(s)**: use only 2 PC from the PCA for the tSNE/UMAP projection
 - **solution/measure**: use a significant portion of PC from the PCA as input for tSNE/UMAP
@@ -188,7 +188,7 @@ Legend:
 - **solution/measure**: use a population size cutoff or state the number
 2. some genes look like dates (1-Mar,...)
 - **source**: seurat/deseq, negative control study
-- **possible reason(s)**: some genes can be interpreted as dates when using excel for data handling [https://www.science.org/doi/10.1126/science.aah4573](https://www.science.org/doi/10.1126/science.aah4573)
+- **possible reason(s)**: some genes can be interpreted as dates when using excel for data handling <https://doi.org/10.1126/science.aah4573>
 - **solution/measure**: never ever use excel or at least make sure that cell type is not "AUTO"
 
 # Further resources