@book { Businessplan,
    title = "Businessplan",
    subtitle = "Aus dem Bereich House-Service incl. Startup-Existenzgründerwettbewerb Feedback",
    author = "Martin {Renner}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832466084",
    url = "https://m.diplom.de/document/221998"
}