To use the sympto-thermal method you need a Basal Thermometer to measure your daily temperatures.
You also need to record your daily observations on charts. You can now download charts and print them at home.
The textbook for our class on the sympto-thermal method of Natural Family Planning is
The Art of Natural Family Planning by John F. Kippley and Sheila K. Kippley.
Recommended reading on natural family planning includes
Fertility, Cycles & Nutrition by Marilyn M. Shannon and Breastfeeding and Natural Child Spacing: How Ecological Breastfeeding Spaces Babies by Sheila K. Kippley
Billings Ovulation is another excellent method of Natural Family Planning. The Ovulation Method: Natural Family Planning by John J. Billings
Our NFP class is offered in association with our local Catholic church. Here are a number of books that explain why the Catholic church favors natural family planning.
Good News About Sex and Marriage: Answers to Your Honest Questions About Catholic Teaching by Christopher West
Love and Responsibility by Karol Wojtyla (Pope John Paul II), H.T. Willetts (Translator)
Of Human Life-Humanae Vitae (Encyclical Letter of Paul VI)