@book { LeistungsbndelbewertunginderHotellerie,
    title = "Leistungsbündelbewertung in der Hotellerie",
    author = "Melanie {Christen}",
    year = "2006",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832496890",
    url = "https://m.diplom.de/document/224765"
}