Rebuttal to: Oral Contraceptives and Venous Thromboembolism

References
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20 Walker AM. Backsliding into correlations. BMJ. http://www.bmj.com/cgieletters/321/7529/477
21 Vandenbroucke JP, Helmerhorst FM, Rosendaal FR. Competing interests and controversy about third generation oral contraceptives. Brit Med J 2000; 320: 381-2.