1. Armstrong, M. C. (2011, March). Implementing education for sustainable development: The potential use of time-honoured pedagogical practice from the progressive era of education. Journal of Sustainability Education, 2. Retrieved from
http://www.jsedimensions.org/wordpress/wpcontent/uploads/2011/03/Armstrong2011.pdf
2. Blessinger, P., Sengupta, E., & Makhanya, M. (2018, September). Higher education’s key role in sustainable development. University World News. The Global Window on Higher Education. Retrieved from
https://www.universityworldnews.com/
3. Bowen, G. A. (2009). Document analysis as a qualitative research method. Qualitative Research Journal, 9, 27–40.
https://doi.org/10.3316/QRJ0902027
.
4. Brown, H. D. & Lee, H. (2015). Teaching by Principles: an interactive approach to language and pedagogy. Pearson Education: New York.
5. Bruner, J. (1996). The Culture of Education. Harvard University Press: Cambridge, Massachusetts.