@article{JETPL.97.642,
    title = {},
    author = {,  and , },
    journal = {JETP Lett.},
    volume = {97},
    issue = {9},
    pages = {557},
    year = {2013},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_30290.shtml},
    note = {[Pisma v ZhETF 97, 642 (2013)]}
}