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2. Himes, N. E.: Medical History of Contraception. p. 256, New York, Gamut Press, 1936.
3. Finch, B. E., Green, Hugh: Contraception through the Ages. London, Peter Owen, 1963.
4. The Practitioner: Special Issue on Contraception. London, July 1923.
5. As 1: pp. 50-51.