Ary, D. Jacobs, L. C., & Razavieh, A. (2002). Introduction to research in education (6th ed.). USA: Wodsworth/Thomson Learning.

Benz, C., & Newman, I. (1998). Qualitative-quantitative research methodology : exploring the interactive continuum. Carbondale: Southern Illinois University Press.

Black, T. R.(1999). Doing quantitative research in the social sciences : an integrated approach to research design, measurement and statistics. London : SAGE.  (TSDAS Digital Library : H61 Bla ).

Borg, W., & Borg, M. (1988). Educational research: an introduction. New York : Longman.

Christensen, L. (1988). Experimental methodology. Boston: Allyn and Bacon, Inc.

Christensen, B., & Johnson, B. (2000). Educational research : quantitative and qualitative approaches. Needham Heights, MA: A Pearson Education Company.

Firestone, W. A.(1987). Meaning in method : the rhetoric of quantitative and qualitative research. Educational Researcher, 16, pp. 1-6.

Guba, E., & Lincoln, Y. (1989). Fourth generation evaluation. Newbury Park, California: Sage Publications.   

Helmstadter, G. (1970). Research concepts in human behaviour. New York : Appleson-Century Crofts.

John Arul Phillips (2007). HMEF 5014 Educational research methodology. Kuala Lumpur: OUM.

Kerlinger, F. (1973). Foundations of behavioural research. New York: Holt Rinehart & Winston.

Kuhn, T. (1973). The structure of scientific revolution. Chicago: University of Chicago Press.