@book { BildungsportaleWegweiserimNetz,
    title = "Bildungsportale – Wegweiser im Netz",
    author = "Olaf {Kos} and Rainer {Lehmann} and Elke {Brenstein} and Doreen {Holtsch}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1099056"
}