1. https://www.ada.org/resources/research/science-and-research-institute/oral-health-topics/whitening
2. The role of bleaching in esthetics;Arens;Dent Clin North Am,1989
3. Tooth discolouration by blood: an in vitro histochemical study;Marin;Dent Traumatol,1997
4. Factors influencing successful bleaching of the discoloured root-filled tooth;Brown;Oral Surgery, Oral Medicine, Oral Pathology,1965
5. Management of discoloured teeth;Faunce;Dent Clin North Am,1983