Lund, H., U. Weile, R. Christensen, B. Rostock, A. Downey, E. M. Bartels, B. Danneskiold-Samsøe, and H. Bliddal. “A Randomized Controlled Trial of Aquatic and Land-Based Exercise in Patients With Knee Osteoarthritis”. Journal of Rehabilitation Medicine, vol. 40, no. 2, Feb. 2008, pp. 137-44, doi:10.2340/16501977-0134.