A comparative study on the effects of a monophasic pill containing desogestrel plus 20μgethinylestradiol, a triphasic combination containing levonorgestrel and a monophasic combination containing gestodene on coagulatory factors - Melis, G B; Fruzzetti, F; Nicoletti, I; Ricci, C; Lammer, P; Atsma, W J; Fioretti, P (Contraception, 1991)