@article{PismaZhETF.5.262,
    title = {Stimulated Emission of an Ensemble of Scattering Particles with Negative Absorption},
    author = {Letokhov, V. S.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {5},
    issue = {8},
    pages = {262},
    year = {1967},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_25164.shtml},
}