World Health organization. (2012). International travel and health. World Health Organization.
Chicago-referens (17:e uppl.)World Health organization. International Travel and Health. Geneva, Switzerland: World Health Organization, 2012.
MLA-referens (8:e uppl.)World Health organization. International Travel and Health. World Health Organization, 2012.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.