@book { EinfachSpielen,
    title = "Einfach Spielen",
    subtitle = "Kindheit in der Wirtschaftswunderzeit",
    author = "Manfred {Mühlbeyer}",
    year = "2017",
    publisher = "Omnino Verlag",
    address = "Berlin, Deutschland",
    url = "https://shop.omnino-verlag.de/document/376177"
}