Krasinskij, G. A. On the determination of the perturbations in the motion of close artificial satellites caused by non-sphericity of the Earth. (Russian) Zbl 0276.70023 Astron. Zh. 50, 1076-1084 (1973). MSC: 70M20 PDFBibTeX XMLCite \textit{G. A. Krasinskij}, Astron. Zh. 50, 1076--1084 (1973; Zbl 0276.70023)
Emel’yanov, N. V. A motion of distant satellites. (Russian) Zbl 0267.70006 Astron. Zh. 50, 1289-1297 (1973). MSC: 70F15 PDFBibTeX XMLCite \textit{N. V. Emel'yanov}, Astron. Zh. 50, 1289--1297 (1973; Zbl 0267.70006)