@book { VirtuelleCommunitiesder2Generation,
    title = "Virtuelle Communities der 2. Generation",
    author = "Thomas {Jäckel}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836624725",
    url = "https://m.diplom.de/document/226469"
}