Added citation

README.md

@@ -17,7 +17,15 @@ you can automate analysis (reading trajectories and running contact score accumu
 
 ## Citation
 If you use PyContact in a scientific publication, please cite:
-A citation will be available soon.
+
+__PyContact: Rapid, Customizable, and Visual Analysis of Noncovalent Interactions in MD Simulations__
+
+Maximilian Scheurer, Peter Rodenkirch, Marc Siggel, Rafael C. Bernardi, Klaus Schulten, Emad Tajkhorshid and Till Rudack
+Biophysical Journal, Volume 114, Issue 3, 577-583
+
+DOI: https://doi.org/10.1016/j.bpj.2017.12.003
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+[Link to Full Text Article](http://www.cell.com/biophysj/fulltext/S0006-3495(17)35051-8)
 
 ## About
 Main Developers: Maximilian Scheurer and Peter Rodenkirch