Neidel, Jasper, Detlef Zander, and Matthias H. Hackenbroch. 1992. “Low Plasma Levels of Insulin-Like Growth Factor I in Perthes’ Disease A Controlled Study of 59 Consecutive Children”. Acta Orthopaedica 63 (4):393-98. https://doi.org/10.3109/17453679209154752.