Glymour M Maria
Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 W. 168th Street, Room 1603, New York, NY 10032, USA.
Soc Sci Med. 2008 May;66(9):1895-902; discussion 1903-8. doi: 10.1016/j.socscimed.2007.12.035. Epub 2008 Feb 20.