Update README.md

README.md

@@ -96,7 +96,7 @@ while allowing soft macros (standard-cell clusters) to also find good locations.
 
 ## **Related Links**
 - R. Cheng and J. Yan, "On joint learning for solving placement and routing in chip design'',
-*Proc. NeurIPS*, 2021. [paper](https://arxiv.org/pdf/2111.00234v1.pdf) [Code](https://github.com/Thinklab-SJTU/EDA-AI)
+*Proc. NeurIPS*, 2021. \[[paper](https://arxiv.org/pdf/2111.00234v1.pdf)\] [Code](https://github.com/Thinklab-SJTU/EDA-AI)
 - F. -C. Chang, Y. -W. Tseng, Y. -W. Yu, S. -R. Lee, A. Cioba et al., 
 "Flexible multiple-objective reinforcement learning for chip placement",
 *arXiv:2204.06407*, 2022. [paper](https://arxiv.org/pdf/2204.06407.pdf)