@book { FourthPartyLogisticsinGermany,
    title = "Fourth Party Logistics in Germany",
    author = "Thore {Kroll}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832475604",
    url = "https://m.diplom.de/document/222839"
}