Christov, Ognyan. “Remark on the Non-Integrability of the Perturbed Motion of the Particle in a Central Field in Constant Curvature Spaces”. Ann. Sofia Univ. Fac. Math. and Inf. 93 (December 12, 2001): 25–30. Accessed November 24, 2024. https://ftl5.uni-sofia.bg./index.php/fmi/article/view/199.