Colonius, Fritz, Roberta Fabbri, Russell Johnson, and Marco Spadini. “Bifurcation Phenomena in Control Flows”. Topological Methods in Nonlinear Analysis 30, no. 1 (September 1, 2007): 87–111. Accessed July 22, 2024. https://apcz.umk.pl/TMNA/article/view/TMNA.2007.020.