@book { ArbeitsbuchJohnvonDffel,
    title = "Arbeitsbuch John von Düffel",
    author = "Kai {Bremer} and Melanie {Grumt Suárez}",
    year = "2017",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b11560",
    url = "https://www.peterlang.com/document/1055554"
}