1. Gehrke SH, Lee PI (1990) In: Tyle P (ed) Specialized drug delivery systems: manufacturing and production technology. Marcel Dekker, New York, p 333
2. Tanaka T (1981) Sci Am 244: 124
3. Peppas NA, Barr-Howell BD (1986) In: Peppas NA (ed) Hydrogels in medicine and pharmacy, vol I fundamentals. CRC Press, Boca Raton, FL, p 27
4. Freitas RFS, Cussler EL (1987) Chem Eng Sci 42: 97
5. Gehrke SH, Cussler EL (1989) Chem Eng Sci 44: 559