3Center for Disease Control and Prevention,Swine influenza A (H1N1) infection in two children-southern California,March-April 2009.MMWR Morb Mortal Wkly Rep 2009;58:400-2.
4Center for Disease Control and Prevention,Update:infections with a swine-origin influenza A (H1N1) virus-United States and other countries,April 28,2009.MMWR Morb Mortal Wkly Rep.2009;58:431-3.
5World Health Organization,http://www.who.int/csr/don/2009_04_24/en/index.html
6Lamb RA,Krug RM.Orthomyxoviridae:The viruses and their Replication.In:Fields Virology fourth edition,Knipe DM,Howley PM eds,Lippincott,Philadelphia 2001,pp 1487-1531.