Cita APA (7a ed.)

Billings, J. J. (1972). The ovulation method: The achievement or avoidance of pregnancy by a technique which is safe, reliable and morally acceptable (American edition.). Borromeo Guild.

Cita Chicago Style (17a ed.)

Billings, John J. The Ovulation Method: The Achievement or Avoidance of Pregnancy by a Technique Which Is Safe, Reliable and Morally Acceptable. American edition. Los Angeles: Borromeo Guild, 1972.

Cita MLA (9a ed.)

Billings, John J. The Ovulation Method: The Achievement or Avoidance of Pregnancy by a Technique Which Is Safe, Reliable and Morally Acceptable. American edition. Borromeo Guild, 1972.