Frick Kevin D, Ma Sai
Johns Hopkins Bloomberg School of Public Health, Department of Health Policy and Management, 624 N Broadway, Rm 606, Baltimore, Maryland 21205, USA.
Acad Pediatr. 2009 May-Jun;9(3):136-7. doi: 10.1016/j.acap.2009.02.001. Epub 2009 Mar 20.