@article{JETPL.96.543, title = {}, author = {, and Shestakov, G. N.}, journal = {JETP Lett.}, volume = {96}, issue = {8}, pages = {493}, year = {2012}, doi = {}, url = {http://jetpletters.ru/ps/0/article_29999.shtml}, note = {[Pisma v ZhETF 96, 543 (2012)]} }