1. H. Bondi:Assumption and Myth in Physical Theory (Cambridge, 1967), p. 53.
2. M. A. Tonnelat:Histoire du principes de relativité (Paris, 1974), and references therein.
3. H. Dingle:Science at the Crossroads (London, 1972).
4. L. Jánossy:Theory of Relativity Based on Physical Relativity (Budapest, 1971).
5. S. J. Prokhovnik:The Logic of Special Relativity (Cambridge, 1967).