Bothorel, A. 1982. "Étude Phonétique Et Phonologique Du Breton Parlé à Argol (Finistere-Sud)." Atelier National Reproduction des Thèses, Université Lille III.
Borman, M. B. 1962. "Cofan Phonemes." In Studies in Ecuadorian Indian languages 1, edited by Benjamin F. Elson. 7: 45-59. Summer Institute of Linguistics of the University of Oklahoma.
Borgman, Donald M. 1990. "Sanuma." In Handbook of Amazonian Languages 2, edited by Desmond C. Derbyshire and Geoffrey K. Pullum. 15-248. Mouton de Gruyter.