1. The Anatomy of Judgement;Abercrombie,1960
2. ‘An experiment with free group discussion.’;Barnett;Univ. Quart.,1958
3. ‘Group experience the democratic way’;Baxter,1970
4. ‘Functional roles of group members’;Benne,1970
5. Taxonomy of Educational Objectives. 1. Cognitive Domain.;Bloom,1956