1. Factors affecting failure of intra-uterine devices;Schenker;Harefuah,1968
2. The Shield intra-uterine device;Davis;Am. J. Obstet. Gynec.,1970
3. The Dalkon Shield: A Clinical Evaluation;Ostergard;Contraception,1971
4. Recommended procedures for the statistical evaluation of intra-uterine contraception. Studies in family planning;Tietze;The Population Council,1973