Villamar Becerril Enrique, “Estudios de ADN y el origen de los olmecas”, Arqueología Mexicana, núm. 150, pp. 40-41.(2019)[2]Arxivat 2021-02-27 a Wayback Machine.
«'Oldest' New World writing found». BBC, 14-09-2006 [Consulta: 30 març 2008]. «Ancient civilisations in Mexico developed a writing system as early as 900 BC, new evidence suggests.»
«Writing May Be Oldest in Western Hemisphere.». The New York Times, 15-09-2006 [Consulta: 30 març 2008]. «A stone slab bearing 3,000-year-old writing previously unknown to scholars has been found in the Mexican state of Veracruz, and archaeologists say it is an example of the oldest script ever discovered in the Americas.»
«Oldest Writing in the New World». Science [Consulta: 30 març 2008]. «A block with a hitherto unknown system of writing has been found in the Olmec heartland of Veracruz, Mexico. Stylistic and other dating of the block places it in the early first millennium before the common era, the oldest writing in the New World, with features that firmly assign this pivotal development to the Olmec civilization of Mesoamerica.»
«The Olmecs» (en anglès). Think Quest. Arxivat de l'original el 24 setembre 2009. [Consulta: 12 maig 2023].
Villamar Becerril Enrique, “Estudios de ADN y el origen de los olmecas”, Arqueología Mexicana, núm. 150, pp. 40-41.(2019)[2]Arxivat 2021-02-27 a Wayback Machine.
