1. D.W.Sciama, The Unity of the Universe, Faber and Faber (1959).
2. A.Qadir, The History of Science in Central Asia, ed.A.Qadir Centre for the Study of Central Asian Civilizations, Quaidi-Azam University Press (1978).
3. M.Rees, R.Ruffini and J.A.Wheeler, Black Holes, Gravitational Waves and Cosmology, Gordon and Breach (1976).
4. C.W.Misner, K.S.Thorne and J.A.Wheeler, Gravitation, Freeman (1973).
5. A.Qadir, Special Issue of the Journal of Central Asia, III 197 (1980).