Reference:

Tom Maniatis, E. F. Fritsch, Joseph Sambrook, Molecular cloning-a laboratory manual,  7th edition, Cold Spring Harbor Laboratory, 1982
Primrose, S. et.al. Principles of Gene Manipulation. Oxford: Blackwell Science, 2001.

Webliography:

1. http://www.methodbook.net/dna/agarogel.html
2. www.vivo.colostate.edu/hbooks/genetics/.../gels/agardna.html
3. http://www.molecularstation.com/agarose-gel-electrophoresis/
4. http://www.protocolonline.org/.../Electrophoresis/Agarose_Gel_Electrophoresis/index.html