@book { BusinessImprovementDistricts,
    title = "Business Improvement Districts",
    author = "Saskia {Müller}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836620680",
    url = "https://m.diplom.de/document/226253"
}