1. The travels of Maya merchants in the ninth and tenth centuriesad: investigations at Xuenkal and the Greater Cupul Province, Yucatan, Mexico;Ardren Traci;World Archaeology,2011
2. Caminos y mercados de México Attolini Lecón A., 2010, « Intercambio y caminos en el mundo maya prehispánico ». In A. Attolini Lecón, J. Long Towell (dir.). (pp. 51-78). México: Instituto de Investigaciones Históricas, UNAM/INAH.
3. THE DISTRIBUTION OF CACAO CULTIVATION IN PRE-COLUMBIAN AMERICA1;BERGMANN JOHN F.;Annals of the Association of American Geographers,1969
4. A Linguistic Look at the Olmecs;Campbell Lyle;American Antiquity,1976
5. Pre-hispanic Use of Cocoa