Billings, E., & Westmore, A. (1980). The Billings method of Natural Family Planning: Controlling fertility without drugs or devices (1st American ed.). Random House.
Цитирование в стиле Чикаго (17-е изд.)Billings, Evelyn, и Ann Westmore. The Billings Method of Natural Family Planning: Controlling Fertility Without Drugs or Devices. 1st American ed. New York: Random House, 1980.
Цитирование MLA (8-е изд.)Billings, Evelyn, и Ann Westmore. The Billings Method of Natural Family Planning: Controlling Fertility Without Drugs or Devices. 1st American ed. Random House, 1980.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.