@book { Selbstoptimierung,
    title = "Selbstoptimierung",
    author = "Ralph {Köhnen}",
    year = "2018",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-07071-2",
    url = "https://www.peterlang.com/document/1068012"
}