1. Zahn, H., et al. J. Soc. Cosmet. Chem. 14, 529 (1963).
2. Stein, H., and Guarnaccio, J. Anal. Chem. Acta 23, 89 (1960).
3. Leach, S.J., Aust. J. Chem. 13, 520 (1960).
4. Robbins, C.R. Textile Res. J. 37, 811 (1967).
5. Robbins, C.R. and Bahl, M. J. Soc. Cosmet. Chem. 35, 379 (1984).