Clemens, J. (2000). Evaluating vaccine safety before and after licensure. World Health Organization.
Dyfyniad Arddull ChicagoClemens, J. Evaluating Vaccine Safety Before and After Licensure. World Health Organization, 2000.
Dyfyniad MLAClemens, J. Evaluating Vaccine Safety Before and After Licensure. World Health Organization, 2000.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.