[Efficacy of the Billings' method].
D000328:Adult; D003267:Contraception / Q000379:methods*; D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008593:Menopause; D008598:Menstruation; D010060:Ovulation
D003278:Contraceptives, Oral, Hormonal
Skuteczność metody Billingsa.