@article{PismaZhETF.13.643,
    title = {$Groups_of$ Parallel Penetrating Particles and Their Possible Sources},
    author = {Bibilashvili, M. F.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {13},
    issue = {11},
    pages = {643},
    year = {1971},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_24362.shtml},
}