@article{JETPL.107.574, title = {}, author = {Stishov, S. M.}, journal = {JETP Lett.}, volume = {107}, issue = {9}, pages = {549}, year = {2018}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X18090060}, note = {[Pisma v ZhETF 107, 574 (2018)]} }