Cibere, J., Kopec, J. A., Thorne, A., Singer, J., Canvin, J., Robinson, D. B., Pope, J., Hong, P., Grant, E., Esdaile, J. M. Randomized, double-blind, placebo-controlled glucosamine discontinuation trial in knee osteoarthritis. Arthritis & Rheumatism 2004; 5: 738-45