1. Natural family planning: the contribution of fertility awareness to body and person integration;Klaus,1979
2. Science and the safe period;Hartman;Baltimore: Williams and Wilkins,1962
3. A cooperative method of natural birth control;Nofziger,1979
4. Fine points of the symptothermic method of natural family planning. International Symposium on Natural Family Planning. St.John’s University;Roetzer,1977
5. The menstrual cycle;Vollman;Philadelphia: WB Saunders,1977