@article{JETPL.107.689, title = {}, author = {Punegov, V. I.}, journal = {JETP Lett.}, volume = {107}, issue = {10}, pages = {655}, year = {2018}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X18100132}, note = {[Pisma v ZhETF 107, 689 (2018)]} }