@article{PismaZhETF.15.91,
    title = {Two-frequency Optical Standard},
    author = {Bagaev, S. N. and Dmitriev, A. K. and Chebotaev, V. P.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {15},
    issue = {2},
    pages = {91},
    year = {1972},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_26496.shtml},
}