“…Relevant references to the literature on state model are Bergan, Cancelli, andLuiten (1980), Besel (1973), Dayton and Macready (1976), Emrick (1971, Emrick and Adams (1969), Macready and Dayton (1977, 1980a, 1980b, Reulecke (1977aReulecke ( , 1977b, van der Linden (1980c, 1981c, 1981d, 1981e), Wilcox (1979a, and Wilcox and Harris (1977).…”