@book { PublicPrivatePartnershipPPPundkleineundmittlereUnternehmenKMU,
    title = "Public Private Partnership (PPP) und kleine und mittlere Unternehmen (KMU)",
    author = "Andreas {Zöller}",
    year = "2006",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832494629",
    url = "https://m.diplom.de/document/224593"
}