@book { koMarketing,
    title = "Öko-Marketing",
    subtitle = "Ein Instrument zur Steigerung des umweltbewußten Konsumentenverhaltens",
    author = "Lutz {Altmann}",
    year = "1997",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832405540",
    url = "https://m.diplom.de/document/216488"
}