von Borck, H. G., and D. J. Rhea. “The Effects of Unstructured Outdoor Play over One Academic Year on Motor Coordination and Self-Esteem in Elementary-Aged Children”. Journal of Health and Physical Literacy, vol. 4, no. Supplement 1, Nov. 2025, p. S34, https://www.johpl.org/index.php/johpl/article/view/90.