Links
[1] https://hootsgo.org/?q=node/6438
[2] http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/differentsubrev3.shtml
[3] http://www.chemguide.co.uk/atoms/structures/giantcov.html
[4] http://www.chm.bris.ac.uk/pt/harvey/gcse/covalent.html
[5] http://www.docbrown.info/page04/4_72bond4.htm
[6] http://chemical-bonding.wikispaces.com/Giant+Covalent+Structures
[7] http://www.avogadro.co.uk/structure/chemstruc/network/g-molecular.htm