Cámara Arrigunaga, Felipe Eduardo, et al. “Correlation of the Kellgren-Lawrence Scale With the Outerbridge Classification in Patients With Chronic Gonalgia”. Revista Colombiana De Ortopedia Y Traumatología, vol. 34, no. 2, July 2020, pp. 160-6, doi:10.1016/j.rccot.2020.06.012.