@article{PismaZhETF.48.297,
    title = {Gravitational instantons and the branching off of the expanding universe},
    author = {Rubakov, V. A. and Tinyakov, P. G.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {48},
    issue = {6},
    pages = {297},
    year = {1988},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_16719.shtml},
}