Снижение уровня вакцинации против кори в некоторых общинах: D. A. Salmon, M. Haber, E. J. Gangarosa, et al., Health Consequences of Religious and Philosophical Exemptions from Immunization Laws: Individual and Societal Risks of Measles, Journal of the American Medical Association 281 (1999): 47–53; D. R. Feikin, D. C. Lezotte, R. F. Hamman, et al., Individual and Community Risks of Measles and Pertussis Associated with Personal Exemptions to Immunization, Journal of the American Medical Association 284 (2000): 3145–3150.
