@article{JETPL.111.455,
    title = {},
    author = {Ruban, V. P.},
    journal = {JETP Lett.},
    volume = {111},
    issue = {7},
    pages = {383},
    year = {2020},
    doi = {},
    url = {http://jetpletters.ru/ps/dx/10.31857/S0370274X2007005X},
    note = {[Pisma v ZhETF 111, 455 (2020)]}
}