6[1]Astin A. Achicving Educational Excellence[M]. San Francisco:Jossey-Bass,1985.
7[2]Johnson D W, Johnson R. Learning Together and AlonePrenticcHall. Inc[M]. New Jersey,1994.
8[3]Johnson D W. Johnson R. Social Interdependence and Perccived Acadcmic and Personal Support in the Classroom[J]. Journal Of Social Psychology,1983,120:77-88.
9[4]Tinto V. Dropout from Higher Education: Atheoretical Synthesis of Recent research[J]. Review of Education Research,1975,45(1):89-125.
