@article{JETPL.93.597, title = {}, author = {, and Kupriyanov, M. Yu.}, journal = {JETP Lett.}, volume = {93}, issue = {9}, pages = {539}, year = {2011}, doi = {}, url = {http://jetpletters.ru/ps/0/article_29272.shtml}, note = {[Pisma v ZhETF 93, 597 (2011)]} }