REFERENCES
- Gräfenberg, E.: An intrauterine contraceptive method. In Sanger, M. and Stones, H. M. (Editors): The Practice of Contraception. Proceedings of the Seventh International Birth Control Conference, 1930, pp 33–47.
- Oppenheimer, W.: Prevention of pregnancy by the Gräfenberg ring method. Amer J Obstet Gynec 78: 446–454, 1959.
- Ishihama, A.: Clinical studies on intrauterine rings. Especially the present state of contraception in Japan and the experiences in the use of intrauterine rings. Yokohama Med Bull 10: 89–105, 1959.
- Vaughn, B. J. and Dominguez, H.: The double coil in Dade County. In Sobrero, A. J. and Lewit, S. (Editors): Advances in Planned Parenthood. New York, Excerpta Medica Foundation, 1969, pp 88–94.
- Schifrin, B. S., Dominguez, H. and Spellacy, W. N.: Uterine perforation with an intrauterine device. Case report and review of literature. J Florida Med Ass 56: 184–186, 1969.
- Food and Drug Administration Advisory Committee on Obstetrics and Gynecology: Report on Intrauterine Devices. Washington, D.C., U.S. Government Printing Office, January 1968.
- Tietze, C.: Report on a new IUCD: The double coil. In Sobrero, A. J. and Lewit, S. (Editors): Advances in Planned Parenthood. New York, Excerpta Medica Foundation, 1968.
- Allan, F. N.: Birth control by intrauterine devices. JAMA 207: 121 (January 6) 1969.