@book { DerFhrungscoach,
    title = "Der Führungscoach",
    subtitle = "Führungskräfteentwicklung nach dem Fünf-Stufen-Modell",
    author = "Thomas {Armbrüster}",
    year = "2017",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1219082"
}