@book { Pferdekardiologie,
    title = "Pferdekardiologie",
    author = "Heidrun {Gehlen}",
    year = "2010",
    publisher = "Schlütersche Verlagsgesellschaft mbH & Co. KG",
    address = ", Deutschland",
    url = "https://schluetersche.openpublishing.com/document/403627"
}