@article{VMUMM_1991_1_a22,
     author = {D. Zekovi\'c},
     title = {Examples of nonlinear nonholonomic constraints in classical mechanics},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {100--103},
     year = {1991},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1991_1_a22/}
}