00462nas a2200145   4500000000100000000000100001008004100002100001900043700001600062700002100078245016700099300001200266490000600278022003200284       2014                            d1 aY. Vinogradova1 aC. Coupland1 aJ. Hippisley-Cox00aExposure to combined oral contraceptives and risk of venous thromboembolism: a protocol for nested case-control studies using the QResearch and the CPRD databases  ae0044990 v4  a2044-6055 (Print) 2044-6055