@book { DasMittelalter,
    title = "Das Mittelalter",
    author = "Janine {Bigot}",
    year = "2001",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640006908",
    url = "https://www.hausarbeiten.de/document/102304"
}