@article{IVM_2015_5_a8,
     author = {D. M. Polyakov},
     title = {On spectral properties of fourth order differential operator with periodic and semiperiodic boundary conditions},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {75--79},
     publisher = {mathdoc},
     number = {5},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2015_5_a8/}
}