@article{PismaZhETF.30.14,
    title = {Two-roton bound state in helium II},
    author = {Blagoveshchenskii, M. M. and Dokukin, E. B. and Kozlov, Zh. A. and Parfenov, V. A.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {30},
    issue = {1},
    pages = {14},
    year = {1979},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_20570.shtml},
}