1. Human Ovulation and Fertility;Farris,1956
2. Periodic Fertility and Sterility in Women: A National Method of Birth Control;Knaus,1934
3. Conception Period in Women;Ogino,1934
4. The determination of the time of Ovulation;Speck;Obst. & Gynec. Surv.,1959
5. The clinical signs of ovulation. A survey of opinion;Sturgis;Fertil. & Steril.,1950