Endangered Languages Catalogue Project. Compiled by research teams at University of Hawai'i Mānoa and Institute for Language Information and Technology (LINGUIST List) at Eastern Michigan University . (2012) ·

Ethnologue: Languages of the World, 16th Edition (2009) . (2009) · edited by M. Paul Lewis · SIL International http://www.ethnologue.com/

Plains Indian Sign Language . Wikipedia. https://en.wikipedia.org/wiki/Plains_Indian_Sign_Language

The World Atlas of Language Structures . (2005) · edited by Bernard Comrie and David Gil and Martin Haspelmath and Matthew S. Dryer · Oxford University Press

Nonspeech Communication Systems ( pp. 275-289 ) . Taylor, Allan R. (1996) · In Handbook of North American Indians. Volume 17: Languages edited by Goddard, Ives · Smithsonian Institution

Hand Talk: Sign Language Among American Indian Nations . Jeffrey E. Davis (2010) · Cambridge University Press https://books.google.com/books/about/Hand_Talk.html?id=XDsvau6__D4C

Plains Indian Sign Language: A comparative study of alternate and primary signers . Melanie Raylene McKay-Cody (1996) · http://arizona.openrepository.com/arizona/handle/10150/278590