1. G. D. SEARLE, UK Patent Application 2 081 582 (1981).
2. ALZA CORPORATION, UK Patent 2 100 605 (1982).
3. ALZA CORPORATION, US Patent 4 237 885 (1980).
4. THE UPJOHN CORPORATION, US Patent 3 920 805 (1975).
5. G. W. DUNCAN and D. R. KALKWARF, edited by E. S. Hafez and T. N. Eans (Harper and Row, New York, 1973).