@article{VMJ_2021_23_2_a6,
     author = {A. Kh. Stash},
     title = {Properties of {Sergeev} oscilation characteristics of periodic second-order equation},
     journal = {Vladikavkazskij matemati\v{c}eskij \v{z}urnal},
     pages = {78--86},
     publisher = {mathdoc},
     volume = {23},
     number = {2},
     year = {2021},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMJ_2021_23_2_a6/}
}