@book { DeutschimKontaktundimKontrast,
    title = "Deutsch im Kontakt und im Kontrast",
    author = "Katarzyna {Lukas} and Izabela {Olszewska}",
    year = "2015",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-04227-6",
    url = "https://www.peterlang.com/document/1048401"
}