Study of the Billings ovulation method for fertility regulation in Lombardy. Medicina e Morale, [S. l.], v. 35, n. 1, 2024. DOI: 10.4081/mem.1985.1423. Disponível em: https://www.medicinaemorale.it/mem/article/view/1423. Acesso em: 6 jun. 2026.