1. Boyatzis, R. E. (1998).Transforming qualitative information. Thematic analysis and code development. Thousand Oaks, CA: Sage.
2. Green, J. & Thorogood, N. (2004).Qualitative methods for health research. London, England: Sage.
3. Rice, P. E. & Ezzy, D. (1999).Qualitative research methods: A health focus. South Melbourne, VIC: Oxford University Press.
4. Strauss, A. & Corbin, J. (1990).Basics of qualitative research: Grounded theory procedures and techniques. Newbury Park, CA: Sage.