@book { EconomiesofScope,
    title = "Economies of Scope",
    author = "Steffen {Liebener}",
    year = "1999",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832415624",
    url = "https://m.diplom.de/document/217404"
}