Books:

John R. Lee - What Your Doctor May Not Tell You About Menopause
Raquel Martin - The Estrogen Alternative
Alan R. Gaby - Preventing and Reversing Osteoporosis
Betty Kamen - Hormone Replacement Therapy: Yes or No?
Jonathan Wright - Natural Hormone Replacement


On the Internet:

Search the net for items related to "Natural Progesterone"
Search the net for the work of Raymond F. Peat, also related to natural progesterone.

Doctors/natural health care providers - find ones knowledgeable in natural health:

MDs - Many are starting to come around to more natural thinking, but it's taking a while. If you find one that is in the know, they can be great.
NDs - Naturopathic doctors. Natural health is their forte, but until more get trained and start to practice, they are hard to find.
DCs - Chiropractors are typically naturally and nutritionally oriented, but not all.
DOs - Osteopathic doctors. Usually naturally oriented, but some have gotten caught up in the pharmaceutical routine.
Dieticians - Often an extension of the medical/pharmaceutical model and their advice is often useless in a "real health" sense. (Example: Look at the dietician formulated food fed to patients at any hospital - typically dead, enzyme depleted, microwaved garbage.) In their defense, some dieticians have moved past their formal training and are very good.
Nutritionists - Some are very good, some are not, and some are just herb salesman.

There are other purveyors of natural health and practice that can be beneficial. You may know of one, or may get a referral from a satisfied customer in your circle of acquaintances.

Cautions:

Sometimes you will find a discussion "proving" a particular therapy. The "proof" being discussed was often a result of some "scientific" double blind study. In reality, double blind studies are only scientific in the narrow range of what is being observed, and where drugs are concerned, many feel that these studies can be greatly manipulated and the numbers "cooked" to substantiate a position.

Hippocrates was an observer of life, and as the role model that began the medical "scientific" process, had an interesting technique to arrive at information helpful to patients. He would send patients with problems out to the gates of the city and have them ask everyone that passed if they ever had or knew anyone that had their particular ailment. When a positive response was found, the patient would ask, "what fixed it?" This is real world feedback. Find an outcome that works consistently in a wide range of people, and you are on your way to finding an answer to the problem. This is an outcome based study.

Natural medicine is based on outcomes. If the desired results don't happen, or don't happen without harm to the patient, the protocol is thrown out. If the outcome works and no harm is done, it's used.  Since most natural health practitioners (MDs or otherwise) typically use known "no harm" substances that have been in use for years, in some cases thousands of years, double blind studies have never been done. The results and experience speak for themselves.

Be aware of these things as you do your research.