References

  Colors and Shapes <http://www.sugarcreek.k12.oh.us/schools/stephenbell/academics/Bolton/shapesPage1.htm>

  Shapes and Colors <http://www.arches.uga.edu/~lisa56/lessonpage.html>

 Hong-Kong Education City <http://www.hkedcity.net/resources/vgal/>

New Space <http://www.newspace.com.tw/free/mater.asp>

Sheng Web <http://nknucc.nknu.edu.tw/~s1378/wjs-1307.htm>