@article{JETPL.107.537,
    title = {},
    author = {Volovik, G. E.},
    journal = {JETP Lett.},
    volume = {107},
    issue = {8},
    pages = {516},
    year = {2018},
    doi = {},
    url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X18080131},
    note = {[Pisma v ZhETF 107, 537 (2018)]}
}