@book { ProblemedesDatabaseMarketingimLadeneinzelhandel,
    title = "Probleme des Database Marketing im Ladeneinzelhandel",
    author = "Ulrich {Heider}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832434861",
    url = "https://m.diplom.de/document/219152"
}