@article{PismaZhETF.2.182,
    title = {Concerning the Difference Between $\nu_\mu$ and $\nu_e$},
    author = {Ushakov, V. V.},
    journal = {Письма в ЖЭТФ},
    volume = {2},
    issue = {4},
    pages = {182},
    year = {1965},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_24494.shtml},
}