del Carmen Rodríguez Martínez, Ponciano Ortíz Ceballos, Michael D. Coe, Richard A. Diehl, Stephen D. Houston, Karl A. Taube, Alfredo Delgado Calderón, Oldest Writing in the New World, "Science", Vol 313, Sep 15 2006, pp1610–1614.
del Carmen Rodríguez Martínez, Ponciano Ortíz Ceballos, Michael D. Coe, Richard A. Diehl, Stephen D. Houston, Karl A. Taube, Alfredo Delgado Calderón, Oldest Writing in the New World, "Science", Vol 313, Sep 15 2006, pp1610-1614.