@book { LanguageMaintenanceLanguageAttrition,
    title = "Language Maintenance – Language Attrition",
    author = "Roman {Laskowski}",
    year = "2015",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-02694-8",
    url = "https://www.peterlang.com/document/1046326"
}