@article{JETPL.99.552, title = {}, author = {Volovik, G. E. and Zubkov, M. A.}, journal = {JETP Lett.}, volume = {99}, issue = {8}, pages = {481}, year = {2014}, doi = {}, url = {http://jetpletters.ru/ps/0/article_30764.shtml}, note = {[Pisma v ZhETF 99, 552 (2014)]} }