@book { Sturzflug,
    title = "Sturzflug",
    author = "Uta-Maria {Heim}",
    year = "2013",
    publisher = "hey! publishing",
    address = "München, Deutschland",
    doi = "10.3239/9783942822992",
    url = "https://www.heypublishing.com/document/263725"
}