@book { DieBesteuerungvonRentenversicherungen,
    title = "Die Besteuerung von Rentenversicherungen",
    author = "Thomas {Ibers}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832475000",
    url = "https://m.diplom.de/document/222764"
}