@article{JETPL.105.261, title = {}, author = {, and Valkov, A. Yu.}, journal = {JETP Lett.}, volume = {105}, issue = {5}, pages = {283}, year = {2017}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X17050022}, note = {[Pisma v ZhETF 105, 261 (2017)]} }