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.
P. Stefanoff, M. Rosinska, G. Karczewski, und A. Zielinski. Euro Surveillance: Bulletin Européen Sur Les Maladies Transmissibles = European Communicable Disease Bulletin, (März 2008)PMID: 18445440.
A. Wilder-Smith, K. Goh, T. Barkham, und N. Paton. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America, 36 (6):
679--83(März 2003)PMID: 12627350.