@article{PismaZhETF.11.227,
    title = {Gravitational Fields of the Third Type},
    author = {Petrov, A. Z.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {11},
    issue = {4},
    pages = {227},
    year = {1970},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_26097.shtml},
}