1. The contribution of ultrasonography to intrauterine contraception;Defoort;Contracept. Deliv. Syst.,1981
2. Ultrasonic detection, localization and identification of intrauterine contraceptive devices;Janssens;Contraception,1973
3. Ultrasonic localization of missing intrauterine contraceptive devices;McAdrel;Acta. obstet. gynaec. scand.,1977
4. Atlas of hysterographic studies of the IUD — holding uterus;Kamal,1979
5. IUD physiology. Advoidance of the dimensional incompatibility as the main reason for side-effects in intrauterine contraception;Kurz;Contraception,1981