1. World Health Organization. Pandemic (H1N1) 2009—update 101. 2010 May 21 [cited 2010 May 22]. http://www.who.int/csr/don/2010_05_21/en/print.html
2. Robert Koch Institute. Influenza—weekly report, Germany, 2010 [in German] [cited 2010 May 19]. http://influenza.rki.de/Wochenberichte/2009_2010/2010-19.pdf
3. 2009 pandemic influenza A (H1N1) virus infections—Chicago, Illinois, April–July 2009.;Centers for Disease Control and Prevention;MMWR Morb Mortal Wkly Rep,2009
4. Kelly H, Grant K. Interim analysis of pandemic influenza (H1N1) 2009 in Australia: surveillance trends, age of infection and effectiveness of seasonal vaccination. Euro Surveill. 2009;14:pii:19288.
5. European Center for Disease Prevention and Control. Risk assessment. Pandemic H1N1 2009 [cited 2009 Dec 20]. http://ecdc.europa.eu/en/healthtopics/H1N1/Documents/1001_RA_091217.pdf