1. Atebe HU 2008.Students’ van Hiele Levels of Geometric Thought and Conception in Plane Geometry: A Collective Case Study of Nigeria and South Africa.Ph. D. Thesis, Unpublished. South Africa: Rhodes University.
2. Atebe HU, Schafer M 2009. The Face of Geometry Instruction and Learning Opportunities in Selected Nigerian and South African High Schools:Paper Presented in the 17th Annual Conference of the Southern African Association for Research in Mathematics, Science and Technology Education (SAARMSTE), South Africa, January 19-22.
3. Battista M 2007. The development of geometric and spatial thinking. In: Frank K Lester, Jr.Second Handbook of Research on Mathematics Teaching and Learning.United States of America : Information Age Publishing.
4. Conference Board of the Mathematical Sciences (CBMS) 2001.The Mathematical Education of Teachers. Providence RI and Washington DC: American Mathematical Society and Mathematical Association of America.
5. Clements DH 2004. Perspective on the child’s thought and geometry. In: TP Carpenter, JA Dossey, JL Koehler (Eds.):Classics in Mathematics Education Research. Reston, VA: NCTM,