1. World Health Organization. Resolución WHA41.28, WHA41/1988/ REC/1.
2. Progress toward global poliomyelitis eradication, 2000;Wkly Epidemiol Rec,2001
3. Certification of poliomyelitis eradication. WHO Western Pacific Region, October 2000;Wkly Epidemiol Rec,2000
4. World Health Organization. Europe achieves historic milestone as Region is declared polio-free. Press release EURO 12/02, 21 June 2002.
5. Apparent global interruption of wild poliovirus type 2 transmission;MMWR,2001