Treble, N. J., R. Owen, and A. M. K. Rickwood. “Classification of Congenital Abnormalities of the Sacrum: Patterns of Associated Dysfunctions”. Acta Orthopaedica 59, no. 4 (January 1, 1988): 412–416. Accessed May 14, 2026. https://actaorthop.org/actao/article/view/22786.