@article{JETPL.103.168, title = {}, author = {Belavin, A. and , and , }, journal = {JETP Lett.}, volume = {103}, issue = {3}, pages = {152}, year = {2016}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X16030024}, note = {[Pisma v ZhETF 103, 168 (2016)]} }