@book { TeensimNetz,
    title = "Teens im Netz",
    author = "Sara {Steffens}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832464431",
    url = "https://m.diplom.de/document/221867"
}