1. H.I. Brown, Observation and Objectivity, Oxford University Press, New York and Oxford 1987, p. 183.
2. A. Eddington, The Nature of the Physical World, New York 1928, p.ix f.
3. B.C. van Fraassen, The Scientific Image, Oxford University Press, Oxford 1980, pp. 15–19.
4. C.A. Hooker, “Systematic Realism”, Synthese 26, Dordrecht 1974, p. 463.
5. D. Shapere, “The Concept of Observation in Science and Philosophy”, Philosophy of Science 49, 1982, 485–525, p.492.