1. Clinical studies on intrauterine rings: especially the present state of contraception in Japan and the experiences in the use of intrauterine rings;Ishihama;Yokohama Med J,1959
2. Prevention of pregnancy by the Grafenberg ring method;Oppenheimer;Amer J Obstet Gynec,1959
3. Endometrial effects of an intrauterine contraceptive device;Morese;Obstet Gynec,1966
4. Reactions of human endometrium to the intrauterine device: Correlation of the endometrial histology with the bacterial environment of the uterus following short term insertion of the IUD;Moyer;Amer J Obstet Gynec,1970
5. Intrauterine contraceptive devices: the recognition and management of uterine perforations;Ledger;Obstet Gynec,1966