Penny, Ralph.Variation and Change in Spanish. — Cambridge University Press, 2000. — С. 199.. — «Whatever might be claimed by other centres, such as Valladolid, it was educated varieties of Madrid Spanish that were mostly regularly reflected in the written standard.».
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Gastón Carrillo Herrera, «Tendencias a la unificación idiomática hispanoamericana e hispánica», in Presente y futuro de la lengua española, Volume II (Madrid: Ediciones de Cultura Hispánica, 1964), pp. 17-34. Quoted in Alberto Gómez Font, Donde dice… debiera decir… (Buenos Aires: Áncora, 2006), p. 240.
