@book { HeidiInEinfacherSprache,
    title = "Heidi: In Einfacher Sprache",
    author = "Spyri {Johanna} and André {Graf}",
    year = "2024",
    publisher = "adlima GmbH",
    address = ", Deutschland",
    url = "https://tolino.openpublishing.com/document/1485950"
}