@book { Weltraumtourismus,
    title = "Weltraumtourismus",
    subtitle = "Die Kommerzialisierung des Alls",
    author = "Patricia {Franjkovic}",
    year = "2016",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    url = "https://m.diplom.de/document/321979"
}