@book { DieLiteraturdesMittelalters,
    title = "Die Literatur des Mittelalters",
    author = "Frank {Sandig}",
    year = "2004",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640072071",
    url = "https://www.hausarbeiten.de/document/109020"
}