http://blog.chinatraveldepot.com/2011/07/the-four-great-inventions/
http://www.chinaculture.org/gb/en_madeinchina/node_2498.htm
http://www.chinainfoonline.com/Chinese_Culture/The_Four_Great_Inventions.htm
http://www.chinavideoclips.net/educational-videos/inventions
Paper/Printing
http://www.ducksters.com/history/china/inventions_technology.php
http://www.absolutechinatours.com/china-travel/Four-Inventions.html
Compass/Magnets