@book { HenrichSteffens,
    title = "Henrich Steffens",
    author = "Marit {Bergner}",
    year = "2016",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-06806-1",
    url = "https://www.peterlang.com/document/1049859"
}