Référence: The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple s sexual behaviour during the fertile time: a prospective longitudinal study
Frank-Herrmann, P.; Heil, J.; Gnoth, C.; Toledo, E.; Baur, S.; Pyper, C.; Jenetzky, E.; Strowitzki, T.; Freundl, G. The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple s sexual behaviour during the fertile time: a prospective longitudinal study. Human Reproduction (Oxford, England) 2007: PMID: 17314078