1. Ranking of contraceptive methods by levels of effectiveness;Tietze,1970
2. The effectiveness of the sympto-thermal method of natural family planning;Rice,1977
3. A prospective multicenter trial of the ovulation method of natural family planning. II. The effectiveness phase;Fertil Steril,1981
4. Conference summary: presentation on natural family planning;Gross,1986
5. Fertility awareness jet age rhythm method;Djerassi;Science,1990