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/

Atlas of the World’s Languages in Danger . Christopher Moseley (ed.) (2010) · UNESCO Publishing http://www.unesco.org/culture/en/endangeredlanguages/atlas

World Oral Literature Project . http://www.oralliterature.org

Language endangerment in South America: The clock is ticking ( pp. 167-234 ) . Crevels, Mily (2012) · In The Indigenous Languages of South America: A Comprehensive Guide edited by Lyle Campbell and Veronica Grondona · Mouton de Gruyter

Tribes of the Eastern Bolivia and the Madeira Headwaters ( pp. 381-454 ) . Alfred Métraux (1948) · In The Tropical Forest Tribes Handbook of South American Indians · Vol. 3 · edited by Julian H. Steward · Smithsonian Institution, Washington: Bureau of American Ethnology

The Native Tribes of Eastern Bolivia and Western Matto Grosso . Alfred Métraux (1942) · Bureau of American Ethnology: Bulletin · Vol. 134 · Washington, D.C.: Smithsonian Institution

Los Guarayú ( pp. 158-190 ) . Max Schmidt (1936) · Revista de la Sociedad Científica del Paraguay. III

Grammatik der Guarayo-Sprache . Hoeller, Alfredo (1932) · Hall in Tirol: Verlag der Missionsprokura der P.~P.~Franziskaner

Internal classification of the Tupi-Guarani linguistic family ( pp. 107-129 ) . Lemle, Miriam (1971) · In Tupi studies I Summer Institute of Linguistics Publications in Linguistics and Related Fields · Vol. 29 · edited by David Bendor-Samuel · Summer Institute of Linguistics of the University of Oklahoma