@article{PismaZhETF.4.3,
    title = {Stratification of Light Beams in a Nonlinear Medium and the Real Threshold for Self-focusing},
    author = {Raizer, Yu. P.},
    journal = {Письма в ЖЭТФ},
    volume = {4},
    issue = {1},
    pages = {3},
    year = {1966},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_24812.shtml},
}