@book { KundenzufriedenheitimMittelstand, title = "Kundenzufriedenheit im Mittelstand", author = "Daniel {Schallmo}", year = "2004", publisher = "Diplom.de", address = "Hamburg, Deutschland", doi = "10.3239/9783832479206", url = "https://m.diplom.de/document/223166" }