@article{PismaZhETF.13.566,
    title = {Upper Limits of Luminosity of Certain Extragalactiс Objects in the Hard $\gamma$-Ray Region},
    author = {Bratolyubova-Tsulukidze, L. S. and Kalinkin, L. F. and Melioranskii, A. S. and Prilutskii, O. F. and Pryakhin, E. A. and Savenko, I. A. and Yufarkin, V. Ya.},
    journal = {Письма в ЖЭТФ},
    volume = {13},
    issue = {10},
    pages = {566},
    year = {1971},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_24341.shtml},
}