RT Journal Article SR Electronic T1 Rule of thumb JF Canadian Family Physician JO Can Fam Physician FD The College of Family Physicians of Canada SP 1309 OP 1310 VO 53 IS 8 A1 Jaggi, Ricky A1 Morris, Steven YR 2007 UL http://www.cfp.ca/content/53/8/1309.abstract AB