Boshkayev, K.A., et al. “Investigation of a Test Particle Motion in the Equatorial Plane of the Axially Symmetric Gravitational Field in Terms of the Adiabatic Theory”. Хабаршы. Физика сериясы, vol. 2018, no. 1, June 2018, pp. 67-80, https://bph.kaznu.kz/index.php/zhuzhu/article/view/624.