Gęba, Kazimierz, and Wacław Marzantowicz. “Global Bifurcation of Periodic Solutions”. Topological Methods in Nonlinear Analysis 1, no. 1 (March 1, 1993): 67–93. Accessed March 7, 2026. https://apcz.umk.pl/TMNA/article/view/TMNA.1993.008.