Update README.md

README.md

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 license: apache-2.0
 ---
 
-this is the sample dataset for arxiv.org/abs/2502.13442
+this is the sample dataset for arxiv.org/abs/2502.13442
+
+## Citation
+```bibtex
+@article{ouyang2025treecut,
+  title={TreeCut: A Synthetic Unanswerable Math Word Problem Dataset for LLM Hallucination Evaluation},
+  author={Ouyang, Jialin},
+  journal={arXiv preprint arXiv:2502.13442},
+  year={2025}
+}