@book { DieEntscheidungzumAbbruchbeiFuEProjekten,
    title = "Die Entscheidung zum Abbruch bei FuE-Projekten",
    author = "Michael {Happel}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832405878",
    url = "https://m.diplom.de/document/216521"
}