@book { PrmieninBonusprogrammen,
    title = "Prämien in Bonusprogrammen",
    subtitle = "Eine empirische Untersuchung",
    author = "Barbara {Gerner}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836602785",
    url = "https://m.diplom.de/document/228830"
}