@book { DasElektroauto,
    title = "Das Elektroauto",
    subtitle = "Innovative Energieeffizienzsteigerung oder nicht?",
    author = "Björn {Pfeifer}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836634748",
    url = "https://m.diplom.de/document/226939"
}