@article{PismaZhETF.23.141,
    title = {Graviton production in a Friedmann universe},
    author = {Vainer, B. V. and Nasel'skii, P. O.},
    journal = {Письма в ЖЭТФ},
    volume = {23},
    issue = {3},
    pages = {141},
    year = {1976},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_27445.shtml},
}