• Na czym polega metoda Billingsa? — zasady obserwacji i interpretacji.

• Free eBooks, oficjalna strona The Billings Ovulation Method Association - USA boma-usa.org

• How Does The Billings Ovulation Method® Work?, oficjalna strona Metody Owulacji Billingsa billings.life: 

  1. Key to Fertility Control - the Mucus;

  2. Basic Infertile Pattern;

  3. Changing Pattern of Fertility;

  4. The Peak of Fertility;

  5. The Post-Ovulatory Infertile Phase;

  6. Keeping a Record.

• Frequently Asked Questions, oficjalna strona Metody Owulacji Billingsa billings.life.

Billings Ovulation Method Association-USA — An introduction to how to make observations for the Billings Ovulation Method®

Billings LIFE — The menstrual cycle and your body's natural signal of fertility - cervical mucus

Billings LIFE — Audio-Visual Presentation of the Billings Ovulation Method™

WOOMB International — Introduction to the Billings Ovulation Method®

WOOMB International — Billings Ovulation Method® and the Phases of the Cycle

Billings LIFE — Billings LIFE Webinar Tracking Fertility Tracking Health