@article{PismaZhETF.9.225,
    title = {Simultaneous Generation of Two Waves of Double Frequency in a Nonlinear Crystal},
    author = {Golovei, M. P. and Kosourov, G. I.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {9},
    issue = {4},
    pages = {225},
    year = {1969},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_25314.shtml},
}