@article{PismaZhETF.20.139,
    title = {Investigation of the mechanism of broadening of resonance lines in ruby by the photon echo method},
    author = {Kopvillem, U. Kh. and Nagibarov, V. P. and Pirozhkov, V. A. and Samartsev, V. V. and Usmanov, R. G.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {20},
    issue = {2},
    pages = {139},
    year = {1974},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_27209.shtml},
}