@article{TVIM_2020_2_a3,
     author = {U. I. Nikitin and A. N. Saharov},
     title = {Special trigonometric series in the problem of periodic solutions},
     journal = {Taurida Journal of Computer Science Theory and Mathematics},
     pages = {61--75},
     year = {2020},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TVIM_2020_2_a3/}
}