@article{JETPL.105.424, title = {}, author = {, and , and Mazur, E. A.}, journal = {JETP Lett.}, volume = {105}, issue = {7}, pages = {430}, year = {2017}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X17070037}, note = {[Pisma v ZhETF 105, 424 (2017)]} }