@book { KooperativesLernenausLsungsbeispielen,
    title = "Kooperatives Lernen aus Lösungsbeispielen",
    author = "Thomas {Schröder}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832484095",
    url = "https://m.diplom.de/document/223597"
}