Lashkov, A. and Zhivkov, A. (2009) “Geometry and solutions of the planar problem of two centers of gravitation”, Ann. Sofia Univ. Fac. Math. and Inf, 99, pp. 129–136. Available at: https://ftl5.uni-sofia.bg/index.php/fmi/article/view/117 (Accessed: 4 December 2024).