The Abacus. 4-11-13. <www.historylines.net/history/chinese/abacus.html>
The History of Computers. Feb. 1995. Piedmont Technical University. 4-11-13
<www.ptc.dcs.edu/Moody/comphistory/comphistory_print.html>
Bedoyere, Guy. The First Computers. Pleaseantville, NY: World Almanac Library, 2006.
Cotterell, Arthur. Ancient China. DK Publishing, 2005.
“The Chinese Abacus.” China Culture., 2003. 4-18-13
<www.chinaculture.org/gb/en_chinaway/2004-03/31/content_46515.htm>
The History of Computers. Feb. 1995. Piedmont Technical University. 4-11-13
<www.ptc.dcs.edu/Moody/comphistory/comphistory_print.html>
Bedoyere, Guy. The First Computers. Pleaseantville, NY: World Almanac Library, 2006.
Cotterell, Arthur. Ancient China. DK Publishing, 2005.
“The Chinese Abacus.” China Culture., 2003. 4-18-13
<www.chinaculture.org/gb/en_chinaway/2004-03/31/content_46515.htm>