S. Baker, and G. Dougan. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America, (July 2007)PMID: 17582565.
A. Forsgren, K. Riesbeck, and H. Janson. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America, 46 (5):
726--731(March 2008)PMID: 18230042.