@article{JETPL.109.589, title = {}, author = {, and Tikhonova, O. V.}, journal = {JETP Lett.}, volume = {109}, issue = {9}, pages = {569}, year = {2019}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.1134/S0370274X19090030}, note = {[Pisma v ZhETF 109, 589 (2019)]} }