@article{JETPL.107.340,
    title = {},
    author = {Volovik, G. E.},
    journal = {JETP Lett.},
    volume = {107},
    issue = {5},
    pages = {324},
    year = {2018},
    doi = {},
    url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X18050120},
    note = {[Pisma v ZhETF 107, 340 (2018)]}
}