You can read this book in 30 minutes and understand it. After ordering this book I was recommended "Taking Charge of your Fertility" by a friend. Taking Charge is more complete but uses this information, however. By the time my amazon.com shipment arrived with the second book, I was already pregnant from the first time trying The Ovulation Method (we had tried to get pregnant approximately a year before getting this book). So read it. You can also use it to avoid getting pregnant. It works!
This book is targeted towards Catholics and is based on research from the 1950's. It does not include the basal temperature method, one of the most important methods for tracking fertility patterns. Unless you are Catholic, I recommend getting another book on this topic, such as "Taking Charge of Your Fertility" by Toni Weschler.