@book { MarketingkologischerProdukte,
    title = "Marketing ökologischer Produkte",
    author = "Sven {Majunke}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832435257",
    url = "https://m.diplom.de/document/219189"
}