@book { DASKLEINELEOSAMMELSURIUM,
    title = "DAS KLEINE LEO-SAMMELSURIUM",
    author = "Ulrich Michael {Heissig}",
    year = "2021",
    publisher = "Omnino Verlag",
    address = "Berlin, Deutschland",
    url = "https://shop.omnino-verlag.de/document/1038031"
}