@book { ElectronicCommerceoverMultiplePlatforms,
    title = "Electronic Commerce over Multiple Platforms",
    author = "Stephan {Siehl}",
    year = "1999",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832419912",
    url = "https://m.diplom.de/document/217834"
}