1. Influenza, pandemic flu myth or a real threat?;Brydak,2008
2. World Health Organization. Influenza. Retrieved February 10 2019 Available from: https://www.who.int/influenza/en/
3. Department of Epidemiology of Infectious Diseases and Surveillance, Laboratory for Monitoring and Analysis of the Epidemiological Situation Illness and suspicion of influenza in Poland - Epidemiological report. Retrieved May 9 2019. Available from: http://wwwold.pzh.gov.pl/oldpage /epimeld/grypa/index.htm.
4. Nationwide Influenza Prevention Program. Retrieved June 30 2019 Available from: https://www.opzg.pl
5. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices-United States. 2018–19 influenza season;Grohskopf;MMWR Recomm Rep,2018