@article{JETPL.107.590, title = {}, author = {Mahmoodian, M. M. and Chaplik, A. V.}, journal = {JETP Lett.}, volume = {107}, issue = {9}, pages = {564}, year = {2018}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X18090096}, note = {[Pisma v ZhETF 107, 590 (2018)]} }