National Osteoporosis Foundation, Osteoporosis
http://www.nof.org/osteoporosis/index.htm

National Osteoporosis Foundation
http://www.nof.org/

National Institutes of Health
http://www.nih.gov/PHTindex.htm

National Institutes of Health Osteoporosis and
Related Bone Diseases-National Resource Center
http://www.osteo.org/

Association of Reproductive Health Professionals
http://www.arhp.org/

The North American Menopause Society
http://www.menopause.org

International Osteoporosis Foundation
http://www.osteofound.org/

National Osteoporosis Society (UK)
http://www.nos.org.uk/

Osteoporosis Society of Canada
http://www.osteoporosis.ca/english/home/default.asp?s=1

Specific issues

The National Heart, Lung, and Blood Institute (NHLBI) stops trial of
estrogen plus progestin due to increased breast cancer risk, lack of overall benefit
http://www.nhlbi.nih.gov/new/press/02-07-09.htm

The National Toxicology Program (NTP), within the U.S. Department of Health
and Human Services, listed "estrogen" as a human carcinogen
on "the 10th report on Carcinogens (12/11/02)."
http://ehp.niehs.nih.gov/roc/toc10.html