http://www.physicsclassroom.com/class/estatics/Lesson-1/The-Structure-of... [2]
https://www.nde-ed.org/EducationResources/HighSchool/Electricity/basicst... [3]
http://www.ehs.utoronto.ca/services/radiation/radtraining/module1.htm [4]
http://www.nobelprize.org/educational/physics/matter/1.html [5]
http://en.wikipedia.org/wiki/Matter [6]
Links
[1] https://hootsgo.org/?q=node/6402
[2] http://www.physicsclassroom.com/class/estatics/Lesson-1/The-Structure-of-Matter
[3] https://www.nde-ed.org/EducationResources/HighSchool/Electricity/basicstructure.htm
[4] http://www.ehs.utoronto.ca/services/radiation/radtraining/module1.htm
[5] http://www.nobelprize.org/educational/physics/matter/1.html
[6] http://en.wikipedia.org/wiki/Matter