@book { FinancialPlanningundPortfolioManagementTheorie,
    title = "Financial Planning und Portfolio Management Theorie",
    author = "Matthias {Schindler}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832476694",
    url = "https://m.diplom.de/document/222942"
}