@article{PismaZhETF.9.441,
    title = {Investigation of Parametric Generator with Feedback in only one of the Waves},
    author = {Belyaev, Yu. N. and Kiselev, A. M. and Freidman, G. l.},
    journal = {Письма в ЖЭТФ},
    volume = {9},
    issue = {8},
    pages = {441},
    year = {1969},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_25383.shtml},
}