Update Readme

README.md

@@ -21,6 +21,13 @@ A GRPO-fine-tuned version of Qwen2.5-3B trained on the MATH dataset.
 ## Citation
 
 ```bibtex
+@article{zhao2025learning,
+  title={Learning to Reason without External Rewards},
+  author={Zhao, Xuandong and Kang, Zhewei and Feng, Aosong and Levine, Sergey and Song, Dawn},
+  journal={arXiv preprint arXiv:2505.19590},
+  year={2025}
+}
+
 @article{sha2024deepseekmath,
   title     = {DeepSeekMath: Pushing the Limits of Mathematical Reasoning in Open Language Models},
   author    = {Shao, Zhihong and Wang, Peiyi and Zhu, Qihao and Xu, Runxin and Song, Junxiao and Bi, Xiao and … Guo, Daya},