@book { DiePrinzipalAgentTheorie,
    title = "Die Prinzipal-Agent-Theorie",
    author = "Margarethe {Mathissen}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836628037",
    url = "https://m.diplom.de/document/226693"
}