@article{PismaZhETF.14.503,
    title = {Single-frequency Brillouin laser Using Methane},
    author = {Kovalev, V. I. and Popovichev, V. I. and Ragul'skii, V. V. and Faizullov, F. S.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {14},
    issue = {9},
    pages = {503},
    year = {1971},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_24947.shtml},
}