@book { ProzesskostenrechnunginSAPR3,
    title = "Prozesskostenrechnung in SAP R/3",
    author = "Thomas {Kaltwaßer}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832447533",
    url = "https://m.diplom.de/document/220348"
}