@book { HeinrichderLweunddieKnigskrone,
    title = "Heinrich der Löwe und die Königskrone",
    author = "Maria {Hase}",
    year = "2001",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640008490",
    url = "https://www.hausarbeiten.de/document/102467"
}