@book { LernenamModell,
    title = "Lernen am Modell",
    author = "Martin {Stehli}",
    year = "2000",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638098359",
    url = "https://www.hausarbeiten.de/document/97160"
}