@article{JETPL.97.7, title = {}, author = {Timofeev, A. V.}, journal = {JETP Lett.}, volume = {97}, issue = {1}, pages = {5}, year = {2013}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X13010025}, note = {[Pisma v ZhETF 97, 7 (2013)]} }