title: [Clinical effectiveness of the ovulation method (Billings)].
mesh_terms: D005069:Evaluation Studies as Topic; D005260:Female; D006266:Health Education; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008297:Male; D012252:Natural Family Planning Methods; D010061:Ovulation Detection / Q000379:methods; D011247:Pregnancy
vernacular_title: Eficacia clínica del método de la ovulación (Billings).