Coba jelasin Nota kaki dari Sejarah penulisan nombor purba dalam bahasa melayu dong

Denise Schmandt-Besserat  HomePage , How Writing Came About, University of Texas Press, 1996, ISBN 0-292-77704-3.

Georges Ifrah.  The Universal History of Numbers: From Prehistory to the Invention of the Computer, Wiley, 2000. ISBN 0-471-37568-3.

Hans J. Nissen, P. Damerow, R. Englund, Archaic Bookkeeping, University of Chicago Press, 1993, ISBN 0-226-58659-6.