@article{JETPL.98.72, title = {}, author = {Kukushkin, V. I. and Van?kov, A. B. and Kukushkin, I. V.}, journal = {JETP Lett.}, volume = {98}, issue = {2}, pages = {64}, year = {2013}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X13140026}, note = {[Pisma v ZhETF 98, 72 (2013)]} }