1. Research Design Qualitative and Quantitative Approaches;Creswell,1994
2. Dudley-Evans, T. & St John, M.J. (1998). Developments in English for specific purposes. A multi-disciplinary approach. Cambridge: Cambridge University Press.
3. Hutchinson, T. & Waters, A. (1987). English for specific purposes. A learning centered approach. Cambridge: Cambridge University Press.
4. d. (2002). Toward principled eclecticism in language teaching: The two-dimensional model and the centring principle. TESL-EJ, 5(4). Online available at http://tesl-ej.org/ej20/a1.html.
5. Multi-method evaluation of instruction in engineering classes;Mohanty;Journal of Personnel Evaluation in Education,2005