Heine, Klaus. “Paleopedological Evidence of Human-Induced Environmental Change in the Puebla – Tlaxcala Area (Mexico) During the Last 3,500 Years”. Revista Mexicana de Ciencias Geológicas 20, no. 3 (May 28, 2018): 235–244. Accessed April 11, 2025. https://rmcg.geociencias.unam.mx/index.php/rmcg/article/view/923.