@article{JETPL.97.76, title = {}, author = {, and , }, journal = {JETP Lett.}, volume = {97}, issue = {2}, pages = {70}, year = {2013}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X13020021}, note = {[Pisma v ZhETF 97, 76 (2013)]} }