@inproceedings{Niu:2005:AMIA,
     title = "Analysis of Polarity Information in Medical Text",
     author = "Niu, Yun and Zhu, Xiaodan and Li, Jianhua and Hirst, Graeme",
     year = "2005",
     booktitle = "Proceedings of the Annual Symposium of the American Medical Informatics Association",
     location = "Washington, D.C., USA"
}