World Health Organization. Vaccines and Biologicals: Who vaccine-preventable diseases: monitoring system.
Dyfyniad Arddull ChicagoWorld Health Organization. Vaccines and Biologicals: Who Vaccine-preventable Diseases: Monitoring System.
Dyfyniad MLAWorld Health Organization. Vaccines and Biologicals: Who Vaccine-preventable Diseases: Monitoring System.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.