@book { Projektmarketing,
    title = "Projektmarketing",
    subtitle = "Partizipation und Projekterfolg",
    author = "David {Friedrich}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832483999",
    url = "https://m.diplom.de/document/223587"
}