@book { ETailingorRetailing,
    title = "E-Tailing or Retailing?",
    author = "Doreen {Happatz}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832461317",
    url = "https://m.diplom.de/document/221591"
}