@article{PismaZhETF.44.388,
    title = {Analog of gravity in superfluid $^3He-A$},
    author = {Volovik, G. E.},
    journal = {Письма в ЖЭТФ},
    volume = {44},
    issue = {8},
    pages = {388},
    year = {1986},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_21138.shtml},
}