Shibata, Tetsutaro. “Multiple Interior Layers of Solutions to Perturbed Elliptic Sine-Gordon Equation on an Interval”. Topological Methods in Nonlinear Analysis 15, no. 2 (June 1, 2000): 329–357. Accessed July 22, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2000.023.