Rozendaal RM, Koes BW, van Osch GJ, Uitterlinden EJ, Garling EH, Willemsen SP, Ginai AZ, Verhaar JA, Weinans H, Bierma-Zeinstra SM. 2008. Effect of glucosamine sulfate on hip osteoarthritis: a randomized trial. Annals of Internal Medicine 148(4):268-277