@book { DerStartindieMakrofotografie,
    title = "Der Start in die Makrofotografie",
    author = "Valentin {Gutekunst}",
    year = "2018",
    publisher = "Schlütersche Verlagsgesellschaft mbH & Co. KG",
    address = ", Deutschland",
    url = "https://schluetersche.openpublishing.com/document/441120"
}