1. Early synthetic organic hair dyes;Charle;Manuf. Chem. Aerosol News,1967
2. Landmarks in the evolution of the dyestuff industry during the past half-century;Green;J. Soc. Dyers Colour.,1934
3. http://ec.europa.eu/health/ph_risk/committees/04_sccp/docs/sccp_s_05.pdf
4. http://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_093.pdf
5. Allergy to hair dye;McFadden;Brit. Med. J.,2007