@conference {cao2008selecting,
	title = {Selecting good expansion terms for pseudo-relevance feedback},
	booktitle = {Proceedings of the 31st annual international ACM SIGIR conference on Research and development in information retrieval},
	year = {2008},
	pages = {243{\textendash}250},
	publisher = {ACM},
	organization = {ACM},
	author = {Cao, Guihong and Jian-Yun Nie and Gao, Jianfeng and Robertson, Stephen}
}
