@book { DerprofessionelleProductOwner,
    title = "Der professionelle Product Owner",
    author = "Don {McGreal} and Ralph {Jocham} and Luitgard {Köster}",
    year = "2021",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1221352"
}