@book { EugenOker,
    title = "Eugen Oker",
    author = "Barbara {Neueder}",
    year = "2015",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-05266-4",
    url = "https://www.peterlang.com/document/1049106"
}