Effects on coagulation of levonorgestrel- and desogestrel-containing low dose oral contraceptives: a cross-over study - Middeldorp, S; Meijers, JCM; van den Ende, AE; van Enk, A; Bouma, BN; Tans, G; Rosing, J; Prins, MH; Büller, HR (Thromb Haemost, 2000)