Lange, J., C. S. Fischer, J.-P. . Kühn, H. . Völzke, T. Ittermann, D. . Gümbel, R. . Kasch, L. Haralambiev, R. Laqua, and P. . Hinz. “The neck–shaft Angle: An Update on Reference Values and Associated Factors”. Acta Orthopaedica, vol. 91, no. 1, Nov. 2019, pp. 53-57, doi:10.1080/17453674.2019.1690873.