1)   PERIMON - Cycle calendar 3.6.9 Cycle calendar, contraception and conceiving aid: displays next menstruation, ovulation and infertile days of the female cycle as well as the prediction accuracy - freeware... 2)   Perimon - Natürliche Familienplanung 3.6.1 Natural family planning program to determine up to 12,5 infertile days in the female cycle, next menstruation, the likely ovulation and forecast accuracy on a user friendly basis. For women from 18 to 45 years of age - freeware... 3)   Perimon - Natural Family Planning 3.6.1 Natural family planning program to determine up to 12,5 infertile days in the female cycle, next menstruation, the likely ovulation and forecast accuracy on a user friendly basis. For women from 18 to 45 years of age - freeware...