@article{IVM_1972_2_a6,
     author = {I. P. Iliev and Kh. I. Semerdzhiev},
     title = {Holonomic mechanical systems with two degrees of freedom that admit quadratic integrals},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {51--53},
     publisher = {mathdoc},
     number = {2},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1972_2_a6/}
}