@book { TheEffectiveExecutive,
    title = "The Effective Executive",
    subtitle = "Effektivität und Handlungsfähigkeit in der Führungsrolle gewinnen",
    author = "Peter F. {Drucker} and Fredmund {Malik} and Katrin {Klein}",
    year = "2014",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1190386"
}