Paper citation

README.md

@@ -74,4 +74,13 @@ This software is distributed under the [MIT Licence](https://mit-license.org).
 
 If you use this package for your own work, please consider citing it as :
 
-**Paper is being reviewed, the citation will be available soon.**
+```bibtex
+@misc{guyard2021screen,
+      title={Screen & Relax: Accelerating the resolution of Elastic-net by safe identification of the solution support}, 
+      author={Théo Guyard and Cédric Herzet and Clément Elvira},
+      year={2021},
+      eprint={2110.07281},
+      archivePrefix={arXiv},
+      primaryClass={math.OC}
+}
+```