1. 1. Council Directive of 27 July 1976. On the approximation of the laws of the Member States relating to cosmetic products (76/768/EEC). Annexe III, part 1, reference number 2 . Official Journal of the European Communities, 10 (No. L 262, 27 September 1976, Legislation) 169 (1976).
2. 2. CTFA Standards, Method D 9-2. Thioglycolic Acid and Dithioglycolic Acid in Thioglycolates. Revised method of 10-15-74.
3. 3. H. H. Wisneski, Analysis of cold wave solutions; 10.3 determining of reducing substances. Newburger's Manual of Cosmetic Analysis , 2nd edn p.78 .Association of Official ChemistsInc., Washington DC (1977 ).
4. 4. Commission of the European Communities., Environment and Consumer Protection Service. Working Party on Cosmetics. Subgroup on chemical methods of analysis. Method by P. Bore. Document XI/969/76 . Dosage de l'Acide Thioglycolique dans une Permanente ou un Depilatoire (1976 ).
5. 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole: a new fluorigenic reagent for amino acids and other amines