Add bibtex entry for citations of use to main README

PiperOrigin-RevId: 273996750
Change-Id: Ib803c4e13c8e644b9e5412803a8d038cb382aadf

README.md

@@ -40,3 +40,25 @@ For a longer introduction to the core concepts, formalisms, and terminology,
 including an overview of the algorithms and some results, please see
 [OpenSpiel: A Framework for Reinforcement Learning in Games](https://arxiv.org/abs/1908.09453).
 
+If you use OpenSpiel in a research paper, please cite the paper using the
+following BibTeX:
+
+```
+@article{LanctotEtAl2019OpenSpiel,
+  title     = {{OpenSpiel}: A Framework for Reinforcement Learning in Games},
+  author    = {Marc Lanctot and Edward Lockhart and Jean-Baptiste Lespiau and Vinicius Zambaldi and
+               Satyaki Upadhyay and Julien P\'{e}rolat and Sriram Srinivasan and Finbarr Timbers and
+               Karl Tuyls and Shayegan Omidshafiei and Daniel Hennes and Dustin Morrill and Paul Muller and
+               Timo Ewalds and Ryan Faulkner and J\'{a}nos Kramár and Bart De Vylder and Brennan Saeta and
+               James Bradbury and David Ding and Sebastian Borgeaud and Matthew Lai and Julian Schrittwieser and
+               Thomas Anthony and Edward Hughes and Ivo Danihelka and Jonah Ryan-Davis},
+  year      = {2019},
+  eprint    = {1908.09453},
+  archivePrefix = {arXiv},
+  primaryClass = {cs.LG}
+  journal   = {CoRR},
+  volume    = {abs/1908.09453},
+  url       = {http://arxiv.org/abs/1908.09453},
+}
+```
+