Campbell، Lyle (8 يناير 2019). "How Many Language Families are there in the World?". UPV/EHU Press. ج. 52 ع. 1/2: 133. DOI:10.1387/asju.20195. ISSN:2444-2992.
Campbell، Lyle (8 يناير 2019). "How Many Language Families are there in the World?". UPV/EHU Press. ج. 52 ع. 1/2: 133. DOI:10.1387/asju.20195. ISSN:2444-2992.