@article{PismaZhETF.14.548,
    title = {Two-quantum Cooperative Frequency Conversion of Weak Light Fluxes},
    author = {Ovsyankin, V. V. and Feofilov, P. P.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {14},
    issue = {10},
    pages = {548},
    year = {1971},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_24975.shtml},
}