@article{JETPL.93.3, title = {}, author = {, and , and , }, journal = {JETP Lett.}, volume = {93}, issue = {1}, pages = {1}, year = {2011}, doi = {}, url = {http://jetpletters.ru/ps/0/article_29085.shtml}, note = {[Pisma v ZhETF 93, 3 (2011)]} }