00509nas a2200193   4500000000100000000000100001008004100002100001400043700001700057700001200074700001600086700001400102700001300116700001400129245012200143300001100265490000700276022003200283       2000                            d1 aR. Farmer1 aR. Lawrenson1 aJ. Todd1 aT. Williams1 aK. MacRae1 aF. Tyrer1 aG. Leydon00aA comparison of the risks of venous thromboembolic disease in association with different combined oral contraceptives  a580-900 v49  a0306-5251 (Print) 0306-5251