@article{JETPL.105.491, title = {}, author = {Petrov, E. K. and Silkin, I. V. and , and Chulkov, E. V.}, journal = {JETP Lett.}, volume = {105}, issue = {8}, pages = {502}, year = {2017}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X17080069}, note = {[Pisma v ZhETF 105, 491 (2017)]} }