@book { DieAnalysederKundenzufriedenheitinderFitnessbranche,
    title = "Die Analyse der Kundenzufriedenheit in der Fitnessbranche",
    author = "Thomas {Rieger}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832430634",
    url = "https://m.diplom.de/document/218776"
}