Bitzer J, Amy JJ, Beerthuizen R, Birkhäuser M, Bombas T, Creinin M, Darney PD, Vicente LF, Gemzell-Danielsson K, Imthurn B, Jensen JT, Kaunitz AM, Kubba A, Lech MM, Mansour D, Merki G, Rabe T, Sedlecki K, Serfaty D, Seydoux J, Shulman LP, Sitruk-Ware R, Skouby SO, Szarewski A, Trussell J, Westhoff C. Statement on combined hormonal contraceptives containing third- or fourth-generation progestogens or cyproterone acetate, and the associated risk of thromboembolism. J Fam Plann Reprod Health Care. 2013 Jul; 39(3):156-9.