@book { BildunginderFreizeit,
    title = "Bildung in der Freizeit?",
    author = "Thomas {Gottschlich}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836635189",
    url = "https://m.diplom.de/document/227161"
}