1. American Academy of Cosmetic Dentistry Press releases www.aacd.com/press/releases/Eblast32007_01_31.asp
2. American Dental Association Tooth whitening treatments www.ada.org/public/topics/whitening_faq.asp
3. American Dental Association Accepted over-the-counter products (as of September 25, 2007) www.ada.org/ada/seal/adaseal_consumer_shopping.pdf
4. American Dental Association Acceptance Program Guidelines, Home-Use Tooth Stain Removal Products http://www.ada.org/ada/seal/standards/guide_home_stain.pdf
5. Prevalence of self-assessed tooth discolouration in the United Kingdom;Alkhatib;Journal of Dentistry,2004