Eckerwall, G., Hochbergs, P., Wingstrand, H., & Egund, N. (1994). Sonography and intracapsular pressure in perthes’ disease: 39 children examined 2-36 months after onset. Acta Orthopaedica, 65(6), 575–580. https://doi.org/10.3109/17453679408994607