1. Atlhopheng, J., Molebatsi, C., Toteng, E. and Totolo, O. (1998). Environmental issues in Botswana, Light Books, Gaborone.
2. Bhattacherjee, A. (2012). Social Science Research: Principles, Methods, and Practice, Textbooks Collectio, Tampa.
3. Creswell J. (2009). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches, Sage, New York.
4. Eggen, P. and Kauchak, D. (2007). Educational Psychology. Windows on Classrooms, Merrill Prentice Hall, New Jersey.
5. Boundaries for a Healthy Planet;Foley;Scientific American,2010