Snow, Rachel C. 2001. "Periodic abstinence and calendar method use in Hungary, Peru, the Philippines, and Sri Lanka." Contraception, 64(4): 209-15.
Focus group research was conducted in four countries to understand how couples who use calendar methods determine when they are at risk of pregnancy, what behavior they adopt during the fertile phase, and whether or not they are satisfied with their method. Calendar and periodic abstinence method users do not all know how to make correct calendar calculations of the fertile period, report being sexually active during the fertile period, and desire a more comprehensive approach to sexual behavior during the fertile period. Men's roles in the methods should be enhanced, and credible resources in the community should be enlisted to improve education, information, and communication.