@book { WasistdieKunstwert,
    title = "Was ist die Kunst wert?",
    author = "Katrin H. {Sperling}",
    year = "2005",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832491901",
    url = "https://m.diplom.de/document/224315"
}