@book { HospitalityMarketingimSport,
    title = "Hospitality Marketing im Sport",
    author = "Martin {Mertens}",
    year = "2012",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783656340485",
    url = "https://www.hausarbeiten.de/document/206959"
}