Calvert, Peter (2004). A Political and Economic Dictionary of Latin America: an essential guide. New York: Routledge. p. 14. ISBN1857432118. OCLC57134234
Baker, Colin; Sylvia P. Jones (1998). Encyclopedia of Bilingualism and Bilingual Education. Clevedon: Multilingual Matters. p. 460. ISBN1-85359-362-1. OCLC34932753A referência emprega parâmetros obsoletos |coautor= (ajuda)