@article{JETPL.104.248, title = {}, author = {Ryzhkin, M. I. and , and Sinitsyn, V. V. and Ryzhkin, I. A.}, journal = {JETP Lett.}, volume = {104}, issue = {4}, pages = {248}, year = {2016}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X16160074}, note = {[Pisma v ZhETF 104, 248 (2016)]} }