@article{DAN_1990_312_3_a20,
     author = {M. M. Khapaev},
     title = {On the evolution of planetary orbits},
     journal = {Doklady Akademii Nauk},
     pages = {599--603},
     publisher = {mathdoc},
     volume = {312},
     number = {3},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1990_312_3_a20/}
}