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3. Smith, C. E. Jr., 1968. Chapter 12. Plant Remains. In Byers, D. S. (ed.) Prehistory of the Tehuacán Valley. Vol. 1. U. Texas Press. Austin.
4. — & T. Kerr. 1968. Pre-Conquest plant fibers from the Tehuacán Valley, Mexico. Econ. Bot.22: 354–358.
5. Stephens, S. G. 1968. A cotton boll segment from Coxcatlan cave. In Byers, D. S. (ed.) The pre-history of the Tehuacán Valley. Vol. 1: 256–260. Texas Press. Austin.