Update README

Author: Fanchao-Qi

README.md

@@ -7,21 +7,14 @@
 
 This project contains core data of HowNet and OpenHowNet API developed by THUNLP, which provides a convenient way to search information in HowNet, display sememe trees, calculate word similarity via sememes, etc. You can also visit our [website](https://openhownet.thunlp.org) to enjoy searching and exhibiting sememes of words online.
 
-If you use any data or API provided by OpenHowNet in your research, please cite the following papers:
+If you use any data or API provided by OpenHowNet in your research, please cite the following paper:
 
 	@article{qi2019openhownet,
 	  title={OpenHowNet: An Open Sememe-based Lexical Knowledge Base},
 	  author={Qi, Fanchao and Yang, Chenghao and Liu, Zhiyuan and Dong, Qiang and Sun, Maosong and Dong, Zhendong},
 	  journal={arXiv preprint arXiv:1901.09957},
 	  year={2019},
 	}
-	
-	@inproceedings{dong2003hownet,
-	  title={HowNet-a hybrid language and knowledge resource},
-	  author={Dong, Zhendong and Dong, Qiang},
-	  booktitle={Proceedings of NLP-KE},
-	  year={2003},
-	}
 
 ## HowNet Core Data
 HowNet core data file（`HowNet.txt`）consists of concepts represented by 223,767 Chinese & English words and phrases. Each concept in HowNet is annotated with sememe-based definition, POS tag, sentiment oriatation, examples, etc. Here is an example of how concepts are annotated in HowNet:

README_ZH.md

@@ -6,20 +6,14 @@
 
 本项目存放HowNet核心数据和清华大学自然语言处理实验室（THUNLP）开发的OpenHowNet API，提供方便的义原信息查询、义原树展示、基于义原的词相似度计算等功能。您还可以访问我们的[网站](https://openhownet.thunlp.org)体验义原在线查询和展示功能。
 
-如果您在研究中使用了OpenHowNet提供的数据或API，请引用以下两篇文章：
+如果您在研究中使用了OpenHowNet提供的数据或API，请引用以下论文：
 
 	@article{qi2019openhownet,
 	  title={OpenHowNet: An Open Sememe-based Lexical Knowledge Base},
 	  author={Qi, Fanchao and Yang, Chenghao and Liu, Zhiyuan and Dong, Qiang and Sun, Maosong and Dong, Zhendong},
 	  journal={arXiv preprint arXiv:1901.09957},
 	  year={2019},
 	}
-	@inproceedings{dong2003hownet,
-	  title={HowNet-a hybrid language and knowledge resource},
-	  author={Dong, Zhendong and Dong, Qiang},
-	  booktitle={Proceedings of NLP-KE},
-	  year={2003},
-	}
 
 ## HowNet核心数据
 HowNet核心数据文件（`HowNet.txt`）由223,767个中英文词和词组所代表的概念构成。HowNet为每个概念标注了基于义原的定义以及词性、情感倾向、例句等信息。下面是HowNet中一个概念的示例：