@article{PismaZhETF.7.88,
    title = {Investigation of the frequency Characteristics of an Xe-He Laser with a Diffuse Mirror},
    author = {Ambartsumyan, R. V. and Basov, N. G. and Letokhov, V. S.},
    journal = {Письма в ЖЭТФ},
    volume = {7},
    issue = {3},
    pages = {88},
    year = {1968},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_25583.shtml},
}