@article{JETPL.107.292, title = {}, author = {, and Shestakov, G. N.}, journal = {JETP Lett.}, volume = {107}, issue = {5}, pages = {276}, year = {2018}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X18050028}, note = {[Pisma v ZhETF 107, 292 (2018)]} }