@article{JETPL.104.488, title = {}, author = {, and , and Mazur, E. A.}, journal = {JETP Lett.}, volume = {104}, issue = {7}, pages = {460}, year = {2016}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X16190048}, note = {[Pisma v ZhETF 104, 488 (2016)]} }