1. Hartman Group's Natural Products Census Supplement Report,1999
2. Messing with Mother Nature;Moore;The Washingtonian,1999
3. Evaluation of active enzyme activity in six oral superoxide dismutase products;Beal;Proc 25th Veterinary Orthop Soc,1998
4. New Good Housekeeping Institute study finds drastic discrepancy in potencies of popular herbal supplement;Good Housekeeping Institute,1998
5. Labels' potency claims often inaccurate, analysis finds. Spot check of products finds widely varying levels of key ingredient. But some firms object to testing method and defend their brands' quality;Monmaney;Los Angeles Times,1998