@article{JETPL.102.272, title = {}, author = {Dolganov, P. V. and Dolganov, V. K. and Kats, E. I.}, journal = {JETP Lett.}, volume = {102}, issue = {4}, pages = {242}, year = {2015}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X15160109}, note = {[Pisma v ZhETF 102, 272 (2015)]} }