1. Callahan, Clark and Kellough (2005). Teaching in the Middle and Secondary Schools. Prentice Hall; 8 edition.
2. http://www.nwrel.org/scpd/sirs/3/cu5.html
3. Cotton, K. (2001). Classroom questioning. North West Regional Educational Laboratory.
4. Cox, S. & A. Griffith (2007). Outstanding teaching.
5. Davis , B. G. (1993).Tools for teaching. By Jossey-Bass Inc, Publishers, 350 Sansome Street, Sanfrancisco, California 94104.