@article{JETPL.109.355,
    title = {},
    author = {,  and , },
    journal = {JETP Lett.},
    volume = {109},
    issue = {6},
    pages = {347},
    year = {2019},
    doi = {},
    url = {http://jetpletters.ru/ps/dx/10.1134/S0370274X19060018},
    note = {[Pisma v ZhETF 109, 355 (2019)]}
}