7Hyacinth S N.Intelligent tutoring systems:An overview[J].Artificial Intelligent Review, 1990;4(4) :251-277.
8Tang H,Barden R,Clifion C.A new Learning environment based on hypertext and its techniques[C].In :Lewis R,Otsuki S eds.Advanced Research on Computers in Education,Holland:Elsevier Science Publishers, 1991 : 119-127.
9Alan F S.Using hypertext for computer based learning[J].Computer Educ, 1991 ; 17(2) : 173-179.
10Gray M B,Mictchell P D.How can intelligent CAI better adapt to leamers[J].Computer Educ, 1992; 18( 1 ) :23-28.
