1. Test No. 427: Skin Absorption: In Vivo Method
2. Test No. 428: Skin Absorption: In Vitro Method
3. USFDA 1982. Toxicological principles for the safety assessment of direct food additives and color additives used in food (Redbook I). Bureau of foods, FDA, 1986.
4. USFDA 2000. Toxicological principles for the safety of food ingredients (Redbook 2000); Updated October 2001 & November 2003.