1. Hess, H. T.Kirk-Othmer Encyclopaedia of Chemical Technology;Wiley:New York,1995; Vol.13, p961.
2. Van Weynbergh, J.; Schoebrechts, J.P.; Chaumont-Gistoux, J.C.U.S. Patent 5447706,1995.
3. Henkel, H.; Weber, W.U.S. Patent 1108752,1914.
4. Zhou, B.; Lee, L.K.U.S. Patent 6168775,2001.
5. Gosser, L. W.; Schwartz, J.A. T.U.S. Patent 4772458,1988.