@book { Gallienus,
    title = "Gallienus",
    subtitle = "2., unveränderte Auflage",
    author = "Michael {Geiger}",
    year = "2015",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-05373-9",
    url = "https://www.peterlang.com/document/1047881"
}