@book { HospitalityKooperationennationalinternationalAnalyseVergleich,
    title = "Hospitality Kooperationen (national; international; Analyse; Vergleich)",
    author = "Matthias {Heller}",
    year = "2005",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638365635",
    url = "https://www.hausarbeiten.de/document/37127"
}