1. Compounds interfering with ovum implantation and development
2. Morris, J M and van Wagenen, G. Postcoital oral contraception. Proceedings of the Eighth International Conference of the International Planned Parenthood Federation. Edited by: Hankinson, R, Kleinman, R, Eckstein, P and Romero, H. pp.256–259. London: International Planned Parenthood Federation. Santiago, Chile, April 9–15, 1967
3. Postcoital Contraception With Diethylstilbestrol
4. Choice of ethinyl estradiol as a postcoital pill
5. The use of estrogens as postcoital contraceptive agents