World Health Organization. (2007). International travel and health: Situation as on 1 January 2007. World Health Organization.
Chicago-Zitierstil (17. Ausg.)World Health Organization. International Travel and Health: Situation as on 1 January 2007. Geneva: World Health Organization, 2007.
MLA-Zitierstil (9. Ausg.)World Health Organization. International Travel and Health: Situation as on 1 January 2007. World Health Organization, 2007.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.