1. ANDREWS, E. 1947.A History of Scientific English, 310–311. New York: Richard R. Smith.
2. ANSCOMBE, G. E. M. 1963.An Introduction to Wittgenstein's Tractatus, 13London: Hutchinson.
3. BARNES, D., BRTTTON, J. and ROSEN, H. 1969.Language, the Learner and the School, 48–49. Harmondsworth: Penguin.
4. Definition in science teaching