@article{TMF_2018_195_2_a4,
     author = {D.I. Borisov},
     title = {Absence of gaps in a~lower part of the~spectrum of {a~Laplacian} with frequent alternation of boundary conditions in a~strip},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {225--239},
     year = {2018},
     volume = {195},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2018_195_2_a4/}
}