@article{PismaZhETF.39.75,
    title = {Relativistic equations for spin-1/2 particles},
    author = {Frik, R. A.},
    journal = {Письма в ЖЭТФ},
    volume = {39},
    issue = {2},
    pages = {75},
    year = {1984},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_19124.shtml},
}