Moulherat, C.; Tengberg, M.; Haquet, J. R. M. F.; Mille, B. ̂T. (2002). “First Evidence of Cotton at Neolithic Mehrgarh, Pakistan: Analysis of Mineralized Fibres from a Copper Bead”. Journal of Archaeological Science. 29 (12): 1393–1401. doi:10.1006/jasc.2001.0779. Quote: "The metallurgical analysis of a copper bead from a Neolithic burial (6th millennium bc) at Mehrgarh, Pakistan, allowed the recovery of several threads, preserved by mineralization. They were characterized according to new procedure, combining the use of a reflected-light microscope and a scanning electron microscope, and identified as cotton (Gossypium sp.). The Mehrgarh fibres constitute the earliest known example of cotton in the Old World and put the date of the first use of this textile plant back by more than a millennium. Even though it is not possible to ascertain that the fibres came from an already domesticated species, the evidence suggests an early origin, possibly in the Kachi Plain, of one of the Old World cottons.
Huckell, Lisa W. (1993). “Plant Remains from the Pinaleño Cotton Cache, Arizona”. Kiva, the Journal of Southwest Anthropology and History. 59 (2): 147–203. JSTOR30246122.
Frank Lawrence Owsley, "The Confederacy and King Cotton: A Study in Economic Coercion," North Carolina Historical Review 6#4 (1929), pp. 371–397 in JSTOR
