I just recall doing a lot of research. One person I follow on Facebook is a retired medical librarian from the Cleveland Clinic who also has osteoporosis. She follows the medical literature and posts about nutrition. But there is a lot of other info out there--just be sure you are following legitimate sources. My doctor also has approved the supplements I take.

Collard greens are also a good source of calcium, and unlike some other greens (spinach) don't contain large amounts of oxalates which interfere with calcium absorption.