1. Gerstein, T. U.S. patent 3,990,991 (1976).
2. Lang, E.W. U.S. patent 3,400,198 (1968).
3. Parran, J., Jr. U.S. patent 3,489,686 (1970).
4. Parran, J., Jr. U.S. patent 3,580,853 (1971).
5. Hough, P.S.; Huey, H.; Tolgyesi, W. et al. J. Soc. Cosmet. Chem. 27:571 (1976).