@article{JETPL.96.859, title = {}, author = {, and , }, journal = {JETP Lett.}, volume = {96}, issue = {12}, pages = {769}, year = {2012}, doi = {}, url = {http://jetpletters.ru/ps/0/article_30122.shtml}, note = {[Pisma v ZhETF 96, 859 (2012)]} }