Farkas, Csaba, Sándor Kajántó, and Csaba Varga. “Lower Semicontinuity of Kirchhoff-Type Energy Functionals and Spectral Gaps on (sub)Riemannian Manifolds”. Topological Methods in Nonlinear Analysis 61, no. 2 (July 16, 2023): 743–760. Accessed July 22, 2024. https://apcz.umk.pl/TMNA/article/view/45115.