↑Yei at Ethnologue (18th ed., 2015) (subscription required)
↑Evans, Nicholas (2018). "The languages of Southern New Guinea". In Palmer, Bill (ed.). The Languages and Linguistics of the New Guinea Area: A Comprehensive Guide. The World of Linguistics. Vol.4. Berlin: De Gruyter Mouton. pp.641–774. ISBN978-3-11-028642-7.