The contribution of subtle oocyte or sperm dysfunction affection fertilization in endometriosis-associated or unexplained infertility: a controlled comparison with tubal infertility and use of donor spermatozoa. - Hull,M.G.; Williams,J.A.; Ray,B.; McLaughlin,E.A.; Akande,V.A.; Ford,W.C. (Hum Reprod, 1998)