1. Atkins, L. & Wallace, S. (2012). Qualitative Research in Education. London: Sage.
2. Ballantyne, R. & Packer, J. (2002). Nature-based excursions: School students’ perceptions of learning in natural environments. International Research in Geographical and Environmental Education, 11(3), 218–236.
3. Barker, S. Slingsby, D. & Tilling, S. (2002). Teaching Biology outside the classroom: Is it heading for extinction? A report on biology in the 14–19 curriculum. FSC Occasional Publication 72. Preston Montford, Shropshire: Field Studies Council.
4. Berryman, T. (2000). Looking at children’s relationships with nature from a developmental perspective: towards an appropriate curriculum. In P. J. Fonts & M. Gomes (Eds.), Environmental Education and the Contemporary World. Proceedings of the International Congress on Environmental Education and the Contemporary world. 19-20 October 2000. (Lisbon, Institute de Inovacao Educacional).
5. Bixler, R.D., Floyd, M. F. & Hammitt, W.E. (2002). Environmental Socialization: Quantitative Tests of the Childhood Play Hypothesis. Environment and Behaviour, 43(6), 795–818.