@article{JETPL.98.69, title = {}, author = {, and Snigirev, A. M. and , }, journal = {JETP Lett.}, volume = {98}, issue = {2}, pages = {61}, year = {2013}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X13140014}, note = {[Pisma v ZhETF 98, 69 (2013)]} }