Lereim, Paul, Ian Goldie, and Erik Dahlberg. 1974. “Hardness of the Subchondral Bone of the Tibial Condyles in the Normal State and in Osteoarthritis and Rheumatoid Arthritis”. Acta Orthopaedica 45 (1-4):614-27. https://doi.org/10.3109/17453677408989184.