Cappella, A.W., E. Giacchi, G. Pompa, and C. Castagna. “The Natural Methods for the Regulation of Fertility and Culture of Life: Teaching Experience Evaluation”. Medicina e Morale 45, no. 4 (August 31, 1996): 669–682. Accessed June 18, 2025. https://www.medicinaemorale.it/mem/article/view/902.