Hammarström, Harald; Forkel, Robert; Haspelmath, Martin (2019). „Catalogue of languages and families“. Jena: Max Planck Institute for the Science of Human History. Suarchyvuota iš originalo 2020-05-02. Nuoroda tikrinta 2021-09-27.
Hammarström, Harald; Forkel, Robert; Haspelmath, Martin (2019). „Catalogue of languages and families“. Jena: Max Planck Institute for the Science of Human History. Suarchyvuota iš originalo 2020-05-02. Nuoroda tikrinta 2021-09-27.