TY - JOUR T1 - Covert pharmaceutical promotion in free medical journals JF - Canadian Medical Association Journal JO - CMAJ SP - 534 LP - 535 DO - 10.1503/cmaj.110156 VL - 183 IS - 5 AU - Aaron S. Kesselheim Y1 - 2011/03/22 UR - http://www.cmaj.ca/content/183/5/534.abstract ER -