Zhang, Wencai, Zhenghao Ge, and DuanLing Li. “Design of a Self-Folding Composite Variable-Diameter Wheel Structure Based on 4D Printing Technology”. Strojniški vestnik - Journal of Mechanical Engineering 69, no. 3-4 (March 29, 2023): 185–195. Accessed January 10, 2025. http://193.2.78.197/index.php/sv-jme/article/view/359.