Williams Rebecca J, Tse Tony, Harlan William R, Zarin Deborah A
National Library of Medicine, National Institutes of Health, UnitedStates Department of Health and Human Services, Bethesda, USA.
CMAJ. 2010 Oct 19;182(15):1638-42. doi: 10.1503/cmaj.092252. Epub 2010 Jul 19.