1. Outbreak of swine-origin influenza A (H1N1) virus infection—Mexico, March-April 2009;MMWR,2009
2. World Health Organization (WHO). World now at the start of 2009 influenza pandemic. Statement to the press by WHO Director-General Dr. Margaret Chan; 2009. Available: http://www.who.int/mediacentre/news/statements/2009/h1n1_pandemic_phase6_20090611/en/.
3. World Health Organization (WHO). H1N1 in post-pandemic period. Director-General's opening statement at virtual press conference 10 August 2010; 2010. Available: http://www.who.int/mediacentre/news/statements/2010/h1n1_vpc_20100810/en/.
4. World Health Organization (WHO). Pandemic (H1N1) 2009—update 112; 2010a. Available: http://www.who.int/csr/don/2010_08_06/en/.
5. Risk factors for pandemic H1N1 2009 infection in healthcare personnel of four general hospitals;SH Choi;J Infect,2011