@book { GeschftsmodelleimInternet,
    title = "Geschäftsmodelle im Internet",
    author = "Björn {Heede}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832441302",
    url = "https://m.diplom.de/document/219754"
}