@book { SportsponsoringDerKundeistKnig, title = "Sportsponsoring 'Der Kunde ist König'", author = "Tobias {Reisenhofer}", year = "2009", publisher = "Diplom.de", address = "Hamburg, Germany", doi = "10.3239/9783836638968", url = "https://m.diplom.de/document/227405" }