World Health Organization. (2008). International travel and health: Situation as on 1 January 2008. World Health Organization.
Chicago-Zitierstil (17. Ausg.)World Health Organization. International Travel and Health: Situation as on 1 January 2008. Geneva: World Health Organization, 2008.
MLA-Zitierstil (9. Ausg.)World Health Organization. International Travel and Health: Situation as on 1 January 2008. World Health Organization, 2008.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.