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Atebe, Humphrey U, Schäfer, Marc. The nature of geometry instruction and observed learning-outcomes opportunities in Nigerian and South African high schools:. 2013.
Atebe, Humphrey U, Schäfer, Marc. “As soon as the four sides are all equal, then the angles must be 90° each”: children's misconceptions in geometry. 2013.
Atebe, Humphrey U, Schäfer, Marc. Beyond teaching language: towards terminological primacy in learners' geometric conceptualisation. 2010.