@article{JETPL.103.872,
    title = {},
    author = {Ratnikov, P. V.},
    journal = {JETP Lett.},
    volume = {103},
    issue = {12},
    pages = {774},
    year = {2016},
    doi = {},
    url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X16120080},
    note = {[Pisma v ZhETF 103, 872 (2016)]}
}