Effectiveness of exercise in patients with osteoarthritis of hip or knee: nine months' follow up
M E van Baar, J Dekker, R A B Oostendorp, D Bijl, Th B Voorn, J W J Bijlsma
Annals of the Rheumatic Diseases Dec 2001, 60 (12) 1123-1130; DOI: 10.1136/ard.60.12.1123