@article{JETPL.93.69,
    title = {},
    author = {Volovik, G. E.},
    journal = {JETP Lett.},
    volume = {93},
    issue = {2},
    pages = {66},
    year = {2011},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_29112.shtml},
    note = {[Pisma v ZhETF 93, 69 (2011)]}
}