Rydholm, U., Wingstrand, H., Egund, N., Elborg, R., Forsberg, L., & Lidgren, L. (1986). Sonography, arthroscopy, and intracapsular pressure in juvenile chronic arthritis of the hip. Acta Orthopaedica, 57(4), 295–298. https://doi.org/10.3109/17453678608994395