@book { Controlling,
    title = "Controlling",
    subtitle = "Theorien und Konzeptionen",
    author = "Ewald {Scherm} and Gotthard {Pietsch}",
    year = "2015",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1220970"
}