@article{PismaZhETF.18.53,
    title = {Spontaneous positron production by the Coulomb field of a heavy nucleus},
    author = {Popov, V. S.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {18},
    issue = {1},
    pages = {53},
    year = {1973},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_23541.shtml},
}