Phylogenetic analysis of hemagglutinin genes of 40 H9N2 subtype avian influenza viruses isolated from poultry in China from 2010 to 2011 - Feng Chen; Zhuan-Qiang Yan; Jun Liu; Jun Ji; Shuang Chang; Di Liu; Jian-Ping Qin; Jing-Yun Ma; Ying-Zuo Bi; Qing-Mei Xie (Virus Genes, 2012)