Tavani , M. R. H. “Existence of Three Weak Solutions for Fourth-Order Elastic Beam Equations on the Whole Space”. Ukrains’kyi Matematychnyi Zhurnal 72, no. 12 (December 24, 2020): 1697–1707. Accessed April 7, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/881.