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Barbosa, Plínio A.; Albano, Eleonora C. (2004). „Brazilian Portuguese”. Journal of the International Phonetic Association34 (2): 227–232. DOI:10.1017/S0025100304001756. ISSN0025-1003
Cruz-Ferreira, Madalena (1995). „European Portuguese”. Journal of the International Phonetic Association25 (2): 90–94. DOI:10.1017/S0025100300005223
Ethnologue: Mandarin1026 mill. (848 mill. prvi jezik + 178 mill. drugi jezik), English840 mill. (335 mill. prvi jezik + 505 mill. drugi jezik), Spanish488 mill. (399 mill. prvi jezik + 89,5 mill. drugi jezik), Hindi380 mill. (260 mill. prvi jezik + 120 mill. drugi jezik)
Barbosa, Plínio A.; Albano, Eleonora C. (2004). „Brazilian Portuguese”. Journal of the International Phonetic Association34 (2): 227–232. DOI:10.1017/S0025100304001756. ISSN0025-1003