1. N.N. Li, U.S. Patent 3, 410, (1968), 749.
2. S. Raynal, J.L. Grossiord, M. Seiller and D. Clausse, J. Contr. Released, 26, (1993), 129.
3. S. Matsumoto in: ACS Symposium Series n°272, Am. Chem. Soc., D.O. Shah, ed., Washington D.C, (1987), 415.
4. N. Garti and S. Magdassi, J. Coll. Interface Sci., 104, (1985), 587.
5. L. Potier, Thesis, Universite de Technologie de Compiegne, France, (1993).