@article{JETPL.93.34, title = {}, author = {, and , and , and , }, journal = {JETP Lett.}, volume = {93}, issue = {1}, pages = {31}, year = {2011}, doi = {}, url = {http://jetpletters.ru/ps/0/article_29091.shtml}, note = {[Pisma v ZhETF 93, 34 (2011)]} }