1. Cavagnaro, E., & Curiel, G. (2012). The three levels of sustainability. Sheffield: Greenleaf Publishing.
2. CRE-COPERNICUS (1994). Copernicus Charter: The University Charter of Sustainable Development of the Conference of European Rectors (CRE), Geneva.
3. ISO (2010). Discovering ISO 26000, Brochure, ISBN 978-92-67-10538-3.
4. Jickling, B. (1992). Viewpoint: Why i don’t want my children to be educated for sustainable development. The Journal of Environmental Education,
23(4), 5–8.
5. Kopnina, H. (2011). Education for sustainable development (ESD): The turn away from ‘environment’ in environmental education? Environmental Education Research, 1–19.