@article{PismaZhETF.20.568,
    title = {Stimulated emission in electroluminescent $CdF_2$ :$TR^{3+}$ films},
    author = {Bednarchuk, D. I. and Novoseletskii, N. E. and Filonenko, V. V.},
    journal = {Письма в ЖЭТФ},
    volume = {20},
    issue = {8},
    pages = {568},
    year = {1974},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_27343.shtml},
}