@article{PismaZhETF.17.91,
    title = {Separation  of Nitrogen Isotopes  with a Laser},
    author = {Ambartsumyan, R. V. and Letokhov, V. S. and Makarov, G. N. and Puretskii, A. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {17},
    issue = {2},
    pages = {91},
    year = {1973},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_23465.shtml},
}