@book { KooperativeLernmethodennachNormGreen,
    title = "Kooperative Lernmethoden nach Norm Green",
    author = "Jochen {Schumacher}",
    year = "2015",
    publisher = "BACHELOR + MASTER PUBLISHING",
    address = "Hamburg, Deutschland",
    url = "https://m.bachelor-master-publishing.de/document/298136"
}