[ENH] add bib in readme

README.md

@@ -170,4 +170,23 @@ bridge.test(test_data)
 
 ## References
 
-For more information about ABL, please refer to: [Zhou, 2019](https://link.springer.com/epdf/10.1007/s11432-018-9801-4?author_access_token=jgJe1Ox3Mk-K7ORSnX7jtfe4RwlQNchNByi7wbcMAY7_PxTx-xNLP7Lp0mIZ04ORp3VG4wioIBHSCIAO3B_TBJkj87YzapmdnYVSQvgBIO3aEpQWppxZG25KolINetygc2W_Cj2gtoBdiG_J1hU3pA==) and [Zhou and Huang, 2022](https://www.lamda.nju.edu.cn/publication/chap_ABL.pdf).
+For more information about ABL, please refer to: [Zhou, 2019](https://link.springer.com/epdf/10.1007/s11432-018-9801-4?author_access_token=jgJe1Ox3Mk-K7ORSnX7jtfe4RwlQNchNByi7wbcMAY7_PxTx-xNLP7Lp0mIZ04ORp3VG4wioIBHSCIAO3B_TBJkj87YzapmdnYVSQvgBIO3aEpQWppxZG25KolINetygc2W_Cj2gtoBdiG_J1hU3pA==) and [Zhou and Huang, 2022](https://www.lamda.nju.edu.cn/publication/chap_ABL.pdf).
+
+```latex
+@article{zhou2019abductive,
+  title={Abductive learning: towards bridging machine learning and logical reasoning},
+  author={Zhou, Zhi-Hua},
+  journal={Science China Information Sciences},
+  volume={62},
+  pages={1--3},
+  year={2019},
+  publisher={Science China Press}}
+
+@incollection{zhou2022abductive,
+  title={Abductive Learning},
+  author={Zhou, Zhi-Hua and Huang, Yu-Xuan},
+  booktitle={Neuro-Symbolic Artificial Intelligence: The State of the Art},
+  pages={353--369},
+  year={2022},
+  publisher={IOS Press}}
+```