Engelhart L, Nelson L, Lewis S, Mordin M, Demuro-Mercon C, Uddin S, McLeod L, Cole B, Farr J. Knee injury and osteoarthritis outcome score subscales for patients with articular cartilage lesions of the knee. Am J Sports Med. 2012 Oct 1;40(10):2264-72.
Mansfield CA. A consistent method for calibrating contingent value survey data. South Econ J. 1998;64(3):665-81.