Eradicating polio: the final hurdles.
D002675:Child, Preschool; D003906:Developing Countries; D006801:Humans; D007223:Infant; D011051:Poliomyelitis / Q000453:epidemiology / Q000517:prevention & control*; D023321:Poliovirus Vaccines / Q000008:administration & dosage*
D023321:Poliovirus Vaccines