“…Several members of the Russian school of celestial mechanics, including Valeri Kozlov and Alexander Harin, [43], [45], Alexey Borisov, Ivan Mamaev, and Alexander Kilin, [5], [6], [7], [8], [39], Alexey Shchepetilov, [67], [68], [69], and Tatiana Vozmischeva, [74], revisited the idea of the cotangent potential for the 2-body problem and considered related problems in spaces of constant curvature starting with the 1990s. The main reason for which Kozlov and Harin supported this approach was mathematical.…”