@book { VariettenimSlavischen,
    title = "Varietäten im Slavischen- Су стандартные варианты славянских языков",
    author = "Alexander {Bierich}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1106393"
}