@book { UltraschallKurs,
    title = "Ultraschall-Kurs",
    author = "Christoph F. {Dietrich}",
    year = "2022",
    publisher = "Deutscher Ärzteverlag",
    address = "Köln, Deutschland",
    url = "https://deutscheraerzteverlag.openpublishing.com/document/1174518"
}