1. Bernard RP: IUD performance patterns: a 1970 world review. Int J Gynaecol Obstet 8: 926, 1970.
2. Blake J: Income and reproductive motivation. Popul Stud 21 (3): 185, 1967.
3. Burnhill MS, Birnberg CH: The size and shape of the uterine cavity determined by hysterography with an intrauterine contraceptive device as a marker. Int J Fertil 11: 187, 1966.
4. Campenhout JV, Blanchet P, Beauregard H, Papas S: Amenorrhea following the use of oral contraceptives. Fertil Steril 28 (7): 718, 1977.
5. Chi I, Kessel E, Mitra M: An epidemiologic study of intrauterine contraceptive devices; a preliminary report. In: Risks, benefits and controversies in fertility control, Sciarra JJ, Zatuchni GI, Speidel JJ (eds), Hagerstown, Harper and Row, 1978, p 478ff.