Polio and injections
Polio and injections - Infectious Diseases of Children, edited by Saul Krugman, M.D., Samuel L. Katz, M.D., Anne A. Gershon, M.D., and Catherine M WIlfert, M.D., chapter on "Enteroviral Infections", p. 75.
Polio and injections - from Vaccines, Third Edition, edited by Stanley A. Plotkin, M.D. and Walter A. Orenstein, M.D. (Director, National Immunization Program, Centers for Disease Control), chapter on "Live Attenuated Poliovirus Vaccines", p.371