1. ( 1984) Why Many College Teachers Cannot Lecture? Charles C. Thomas, Springfield.
2. ( 1999) Learning together and alone: Cooperative, competitive and individualistic learning, Allym & Bacon ed., Boston.
3. Effects of Small-Group Learning on Undergraduates in Science, Mathematics, Engineering, and Technology: A Meta-Analysis
4. ( 1989) Cooperation and Competition: Theory and Research, Interaction Book Company, Edina, MN.
5. , ( 2000) Cooperative learning methods: A meta-analysis, Cooperative learning center website (www.clcrc.com).