@article{CHEB_2020_21_2_a16,
     author = {I. K. Kozlov and A. A. Oshemkov},
     title = {Classification of saddle-focus singularities},
     journal = {\v{C}eby\v{s}evskij sbornik},
     pages = {228--243},
     publisher = {mathdoc},
     volume = {21},
     number = {2},
     year = {2020},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/CHEB_2020_21_2_a16/}
}