@book { QualittimWellnessmarkt,
    title = "Qualität im Wellnessmarkt",
    subtitle = "Kundennutzen des Qualitätsmanagements in Thermen",
    author = "Bernd {Güsken}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832485047",
    url = "https://m.diplom.de/document/223709"
}