1. COCKBURN, W.C. & DROZDOV, S.G. Bull. World Health Org.42: 405, 1970.
2. HORSTMAN, D. The Med. Clinics of N. Am.61:681, 1967.
3. SABIN, A.B. Poliomyelitis. Accomplishments of Live Virus Vaccine. In: Proceedings of First International Conf. on Vaccines Against Viral and Rickettsial Diseases of Man, p. 17, Washington, D.C., Pan American Health Org. 1967.
4. RAMOS-ALVAREZ, M. Section A in: Proceedings of First International Conf. on Vaccines Against Viral and Rickettsial Diseases of Man, Washington, D.C., Pan American Health Org. 1967. , p. 213.
5. DROZDOV, S. & COCKBURN, W.C. Poliomyelitis in the Developed and Developing Countries, In: Conference on the Application of Vaccines Against Viral, Rickettsial and Bacterial Diseases of Man, p. 163, Washington, D.C., Pan American Health Org., 1971.