1.
Hart, K.: Chapter 7, Ratio and proportion. In: Children’s understanding of mathematics, 11-16. pp. 88–97. John Murray, London (1981).
2.
Butt, G.: MasterClass in geography education: transforming teaching and learning. Bloomsbury Academic, London (2015).
3.
Jones, M.: The handbook of secondary geography. Geographical Association, Sheffield (2017).
4.
Lambert, D., Jones, M.: Debates in geography education. Routledge, London (2013).