@book { JosephGregor,
    title = "Joseph Gregor",
    subtitle = "Gelehrter – Dichter – Sammler",
    author = "Christiane {Mühlegger-Henhapel}",
    year = "2006",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1099946"
}