Sources

Grand Illusions.com: http://www.grand-illusions.com/napol2.htm

Periodic table of the elements: http://www.edu.uch.gr/~tsigarid/ptoe

Periodic table of the elements at Los Alamos National Library: http://pearl1.lanl.gov/periodic/elements/33.html

Periodic table of the elements: http://kufacts.cc.ukans.edu/cwis/reference/Periodic/periodic.html

Chemical elements.com: http://www.chemicalelements.com/

Periodic table: http://dayah.com/periodic/

Periodic table of the elements: http://www.cs.ubc.ca/cgi-bin/nph-pertab/tab/periodic-table

Webelements: http://www.shef.ac.uk/chemistry/web-elements/As/key.html