Faraj , Iman, and Jasim Khawwaf. “Intelligent Robust Control of Inverted Pendulum Using Hierarchical Sliding Mode and ELM-Based Estimator”. Archive of Mechanical Engineering 73, no. 1 (March 12, 2026): 19–41. Accessed October 19, 2026. https://wydawnictwo.pan.pl/index.php/ame/article/view/7234.