Wenger N S, Shekelle P G
Division of General Internal Medicine, University of California, Los Angeles, 911 Broxton Plaza, Los Angeles, CA 90095-1736, USA.
Ann Intern Med. 2001 Oct 16;135(8 Pt 2):642-6. doi: 10.7326/0003-4819-135-8_part_2-200110161-00002.