Conradie, P. J. creator Du Plessis, P. G. (Pieter George) 1947- text sa Durban Butterworth c1980 2nd ed. monographic eng

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157 p. : ill. P J Conradie, P G du Plessis. Education Audio-visual aids Instructional systems Educational technology Technical aids Teaching Aids and devices 371.334 0409099252 (pbk) 900703 20151023231626.0