@book { ZurckzurZuversicht,
    title = "Zurück zur Zuversicht",
    author = "Maria von {Welser}",
    year = "2013",
    publisher = "hey! publishing",
    address = "München, Deutschland",
    doi = "10.3239/9783942822459",
    url = "https://www.heypublishing.com/document/208580"
}