Marcelli, Cristina, and Francesca Papalini. “Comparison Results and Existence of Bounded Solutions to Strongly Nonlinear Second Order Differential Equations”. Topological Methods in Nonlinear Analysis 36, no. 1 (September 1, 2009): 91–110. Accessed July 6, 2025. https://apcz.umk.pl/TMNA/article/view/TMNA.2009.031.