1. H. Reichenbach, The Philosophy of Space and Time (originally published 1928) (trans. M. Reichenbach and J. Freund), New York, 1957, chapter 1.
2. A. Grunbaum, Philosophical Problems of Space and Time, London, 1964, part i.
3. Hilary Putnam, ‘An Examination of Grunbaum’s Philosophy of Geometry’ in Philosophy of Science. The Delaware Seminar (ed. B. Baumrin), ii, London, 1963.
4. Arthur Fine, ‘Discussion: Physical Geometry and Physical Laws’, Philosophy of Science, 1964, 31, 156–62.
5. A. Einstein, ‘The Foundation of the General Theory of Relativity’ (originally published 1916) in A. Einstein et al., The Principle of Relativity (trans. W. Perrett and G. B. Jeffery), London, 1923.