@book { OnlineMarketing,
    title = "Online Marketing",
    subtitle = "Etablierte Methoden und Trends im Web 2.0 - Eine Expertenbefragung",
    author = "Severina {Kiriakova}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836612883",
    url = "https://m.diplom.de/document/225774"
}