@article{JETPL.109.54, title = {}, author = {Nikitin, M. V. and Pokrovskii, V. Ya. and Zybtsev, S. G. and Frolov, A. V.}, journal = {JETP Lett.}, volume = {109}, issue = {1}, pages = {51}, year = {2019}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.1134/S0370274X19010107}, note = {[Pisma v ZhETF 109, 54 (2019)]} }