@book { BeschwerdemanagementinDienstleistungsunternehmen,
    title = "Beschwerdemanagement in Dienstleistungsunternehmen",
    author = "Thomas {Wilfling}",
    year = "2009",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640327225",
    url = "https://www.hausarbeiten.de/document/127291"
}