@article{JETPL.105.523, title = {}, author = {, and , }, journal = {JETP Lett.}, volume = {105}, issue = {8}, pages = {548}, year = {2017}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X17080148}, note = {[Pisma v ZhETF 105, 523 (2017)]} }