@article{VMUMM_1989_4_a13,
     author = {R. M. Bulatovic},
     title = {Notes on the instability of equilibrium in nonholonomic systems},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {57--60},
     year = {1989},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1989_4_a13/}
}