@book { AufderSuchenachWirklichkeit,
    title = "Auf der Suche nach Wirklichkeit",
    author = "Jürgen {Heumann} and Wolfgang Erich {Müller}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1083704"
}