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3. Hirte, S., Dick, W.-R., Schilbach, E. and Scholz, R.-D., 1990. In ‘Errors, Uncertainties and Bias in Astronomy’, eds. C. Jaschek and F. Murtagh, Cambridge University Press, p. 343.
4. Kharchenko, N.V., Schilbach, E. and Scholz, R.-D., 1993. See poster paper at this Symposium.
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