@book { Coaching,
    title = "Coaching",
    subtitle = "Eine empirische Studie im Raum Aachen und Düren und Darstellung moderner Einsatzfelder",
    author = "Oliver {Barthe}",
    year = "1997",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832403157",
    url = "https://m.diplom.de/document/216300"
}