Sam C.

If you don't think the website you looked at has "enough" or the right kind of information, call and order PE's catalogue. I guarantee it will have all the information you can handle, including all the titles of the PhD/MD level research papers where PE got the information they use. Just beware, these papers will be very "scientifically dense" and you might not be able to interpret them as they are not written for the general public.
Please note that their products are not intended to be for general good health — most of them are actually intended to be used as definitive medications prescribed by doctors to that specific diseases or maladies. That's why (for the most part) you have to purchase them from a health care professional. It would be easy to take some product and get way too high a dosage of some vitamin or other biological and damage an organ (examples could be B6, potassium or Vit A).
Their prices are high because they test each and every batch of product for potency and purity, they do not contain any fillers or binders that could be harmful, do not contain any of the common allergens such as nut tree products and are verified by every organization that does so.
But here's the best part — without any prior appointment, you can show up at their plant in Sudbury, Massachusetts and physically check/inspect the place. All of the research, development and manufacture of their products is done there in Sudbury. Inside looks like bio containment lab with everyone walking around in space suits! Go see it yourself.
By the way, the testing of their products is done by third-party agencies.
In my opinion, they are the best provider of medicinal supplements on the planet. Nice to know we can trust something made by a company again.
Talk to your doctor before taking any product from any supplier! Some people could injure themselves taking even something like a multivitamin. No joke. Use care and medical advice.