World Health Organization. (1995). International travel and health: Vaccination requirements and health advice. World Health Organization.
Dyfyniad Arddull ChicagoWorld Health Organization. International Travel and Health: Vaccination Requirements and Health Advice. Geneva: World Health Organization, 1995.
Dyfyniad MLAWorld Health Organization. International Travel and Health: Vaccination Requirements and Health Advice. World Health Organization, 1995.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.