@article{PismaZhETF.6.700,
    title = {Physical Singularity in a Space Filled with a Nonideal Medium},
    author = {Grishchuk, L. P.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {6},
    issue = {6},
    pages = {700},
    year = {1967},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_25463.shtml},
}