@book { CoachingalsMethodederPersonalentwicklung,
    title = "Coaching als Methode der Personalentwicklung",
    author = "Holger {Okken}",
    year = "2000",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832429515",
    url = "https://m.diplom.de/document/218674"
}