@article{PismaZhETF.11.303,
    title = {Focusing of Light in Cubic Media},
    author = {Talanov, V. I.},
    journal = {Письма в ЖЭТФ},
    volume = {11},
    issue = {6},
    pages = {303},
    year = {1970},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_26119.shtml},
}