1. Actual aspects of travellers medicine;Erovichenkov;Infectious diseases: News, Opinions, Training,2013
2. world tourism highlights;UNWTO,2018
3. Russiatourism. Statistics data. Available at: https://www.russiatourism.ru/contents/statistika/[accessed 24.03.2019] ([In Russian]).
4. Chapter 17. Eastern Europe;Pshenichnaya,2017
5. Travellers' diarrhea;Sundukov;Lechaschi Vrach Journal,2010