@article{MZM_1967_2_5_a13,
     author = {K. M. Tsoi and S. N. Shimanov},
     title = {The stability of periodic motions of autonomous systems with lag},
     journal = {Matemati\v{c}eskie zametki},
     pages = {561--568},
     year = {1967},
     volume = {2},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1967_2_5_a13/}
}