@article{PismaZhETF.21.660,
    title = {Reflection of plane waves from an amplifying medium},
    author = {Kolokolov, A. A.},
    journal = {Письма в ЖЭТФ},
    volume = {21},
    issue = {11},
    pages = {660},
    year = {1975},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_22516.shtml},
}