http://www.timetoast.com/timelines/atomic-scientist
http://www.universetoday.com/60058/democritus-atom/
http://www.iun.edu/~cpanhd/C101webnotes/composition/dalton.html
http://www.abcte.org/files/previews/chemistry/s1_p6.html
ttp://www.qrg.northwestern.edu/projects/vss/docs/Propulsion/1-what-is-an-atom.html