Nilsson, Bo E., and Karl J. Obrant. “Secular Tendencies of the Incidence of Fracture of the Upper End of the Femur”. Acta Orthopaedica 49, no. 4 (January 1, 1978): 389–391. Accessed June 2, 2026. https://actaorthop.org/actao/article/view/29147.