Singer, Ben (Mayo 2005). Una breve historia del caballo en América(en inglés). Canadian Geographic Magazine. Archivado desde el original el 19 de agosto de 2014. «Multiple factors including hunting by early Natives, climate change, and disease are thought to have helped contribute to their demise».
Singer, Ben (Mayo 2005). Una breve historia del caballo en América(en inglés). Canadian Geographic Magazine. Archivado desde el original el 19 de agosto de 2014. «Multiple factors including hunting by early Natives, climate change, and disease are thought to have helped contribute to their demise».