K. Anstey, H. Mack, und N. Cherbuin. The American Journal of Geriatric Psychiatry: Official Journal of the American Association for Geriatric Psychiatry, 17 (7):
542--555(Juli 2009)PMID: 19546653.
L. Archibald, M. den Dulk, K. Pallangyo, und L. Reller. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America, 26 (2):
290--6(Februar 1998)PMID: 9502444.
O. Bilukha, und N. Rosenstein. MMWR. Recommendations and Reports: Morbidity and Mortality Weekly Report. Recommendations and Reports / Centers for Disease Control, 54 (RR-7):
1--21(Mai 2005)PMID: 15917737.