@article{PismaZhETF.18.253,
    title = {Spontaneous single-frequency generation of a solid-state ring laser},
    author = {Mak, A. A. and Ustyugov, V. I.},
    journal = {Письма в ЖЭТФ},
    volume = {18},
    issue = {4},
    pages = {253},
    year = {1973},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_23915.shtml},
}