@article{PismaZhETF.30.499,
    title = {Existence of bi-excitons and trions in germanium},
    author = {Zhidkov, A. E. and Pokrovskii, Ya. E.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {30},
    issue = {8},
    pages = {499},
    year = {1979},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_20679.shtml},
}