A. Wilder-Smith, K. Goh, T. Barkham, and N. Paton. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America, 36 (6):
679--83(March 2003)PMID: 12627350.
WHO. Relevé Épidémiologique Hebdomadaire / Section D'hygiène Du Secrétariat De La Société Des Nations = Weekly Epidemiological Record / Health Section of the Secretariat of the League of Nations, 82 (10):
79--87(March 2007)PMID: 17348094.