
http://en.wikipedia.org/wiki/Covalent_bond
http://chemwiki.ucdavis.edu/Theoretical_Chemistry/Chemical_Bonding/Gener...
http://www.chemguide.co.uk/atoms/bonding/covalent.html
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/valenceframe.html
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html
http://www.csus.edu/indiv/t/toofanj/JThome/students/chem-110/CHE110-CH11...
http://www.sgh.rcs.k12.tn.us/TEACHERS/walrathb/Web_page/power%20points/4...
http://web.chem.ucsb.edu/~feldwinn/Chem1C/Overheads/chapter-14-slides.pdf
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