1. Matson, T.P., and M. Berretz, Soap, Cosmet. Chem. Spec., Nov. 1979.
2. Friberg, S.E., and M. Chiu, J. Dispersion Sci. Technol. 9: (1988–89).
3. Book of ASTM Standards, American Society for Testing Materials, Philadelphia, ASTM D 2024.
4. Ibid. Book of ASTM Standards, American Society for Testing Materials, Philadelphia, ASTM D 1173.