RT Journal Article SR Electronic T1 Oral contraceptives, ABO blood types and thromboembolism JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 1526 OP 1526 DO 10.1503/cmaj.113-2148 VO 185 IS 17 A1 Julian L. Ambrus YR 2013 UL http://www.cmaj.ca/content/185/17/1526.1.abstract AB