@book { GeistesGegenwart,
    title = "Geistes-Gegenwart",
    author = "Franz {Gruber} and Christoph {Niemand} and Ferdinand {Reisinger}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1106390"
}