TY - JOUR AU - D.I. Borisov TI - Absence of gaps in a lower part of the spectrum of a Laplacian with frequent alternation of boundary conditions in a strip JO - Teoretičeskaâ i matematičeskaâ fizika PY - 2018 SP - 225 EP - 239 VL - 195 IS - 2 UR - http://geodesic.mathdoc.fr/item/TMF_2018_195_2_a4/ LA - ru ID - TMF_2018_195_2_a4 ER -