Raatikainen, Timo, Kalervo Väänänen, and Gösta Tamelander. 1990. “Effect of Glycosaminoglycan Polysulfate on Chondromalacia Patellae: A Placebo-Controlled 1-Year Study”. Acta Orthopaedica 61 (5):443-48. https://doi.org/10.3109/17453679008993559.