1. Zahn, H. J. Soc. Cosmet. Chem. 17:687 (1966).
2. Zahn, H.; 4th Int. Hair Sci. Symp., Syburg, West Germany, German Wool Res. Indust. Publ. Abstracts November (1984).
3. Robbins, C. Text. Res. J. 37:811 (1967).
4. Nachtigal, J.; Robbins, C. Text. Res. J. 40:454 (1970).
5. Robbins, C.; Kelly, C. J. Soc. Cosmet. Chem. 20:555 (1969).