http://www.rogerblench.info/Language/Africa/Nigeria/NigOP.htm (全文テキスト(全般))
http://www.rogerblench.info/Language/Africa/Nigeria/Atlas%20of%20Nigerian%20Languages-%20ed%20III.pdf (全文テキスト(全般))
Blench, R. (2012). An atlas of Nigerian languages. Cambridge: N.A.