Capietto, Anna, Jean Mawhin, and Fabio Zanolin. “On the Existence of Two Solutions With a Prescribed Number of Zeros for a Superlinear Two-Point Boundary Value Problem”. Topological Methods in Nonlinear Analysis 6, no. 1 (September 1, 1995): 175–188. Accessed May 27, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.1995.039.