Horlacher, Rebekka. “The Emergence of Physical Education As a Subject for Compulsory Schooling in the First Half of the Nineteenth Century: The Case of Phokion Heinrich Clias and Adolf Spiess”. Nordic Journal of Educational History 4, no. 2 (December 12, 2017): 13–30. Accessed February 6, 2025. https://journals.ub.umu.se/index.php/njedh/article/view/93.