@article{VMUMM_2004_4_a11,
     author = {V. A. Samsonov and T. S. Sumin},
     title = {Stability of equilibrium state of a mechanical system with two degrees of freedom},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {60--62},
     year = {2004},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2004_4_a11/}
}