@article{JETPL.106.14, title = {}, author = {Il?ichov, L. V.}, journal = {JETP Lett.}, volume = {106}, issue = {1}, pages = {12}, year = {2017}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X17130033}, note = {[Pisma v ZhETF 106, 14 (2017)]} }