@book { DieBedeutungvonBenchmarkingimMittelstand,
    title = "Die Bedeutung von Benchmarking im Mittelstand",
    author = "John {Penner}",
    year = "2010",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783842804197",
    url = "https://m.diplom.de/document/228033"
}