Applicable to the calculation of periods of fertility and agenesis of women (Machine-translation by Google Translate, not legally binding)

摘要

A rule for calculating the periods of fecundity and agenesis of women according to the Ogino-Knaus method, characterized by being formed only by two flat discs, metallic or not, about eight centimeters in diameter and superimposed, that rotate freely around the axis that unites them. (Machine-translation by Google Translate, not legally binding)