Mirenghi, E., and M. Tucci. “Some Existence Results for Dynamical Systems on Non-Complete Riemannian Manifolds”. Topological Methods in Nonlinear Analysis, vol. 13, no. 1, Mar. 1999, pp. 163-80, https://apcz.umk.pl/TMNA/article/view/TMNA.1999.008.