1. A number of papers quoted in this presentation were published in the Proceedings of the IAU Colloquium No. 26 on Reference Coordinate Systems for Earth Dynamics held in Torun (26–31 August 1974), edited by B. Kolaczek and G. Weiffenbach and published by the Polish Academy of Sciences. This important book is referred below as “IAU coll. 26, Torùn”.
2. Anderle, R.J. and Tanenbaum, M.C.: 1975, IAU, Coll. 26, Torùn, p. 341.
3. Bacchus, P. and Lacroute, P.: 1974, in “New problems in astrometry”, IAU symposium No. 61, Reidel Publ. Co., W. Gliese et al. editors, p. 277.
4. Calame, O.: 1976, The Moon, Vol. 15, p. 343.
5. Duncombe, R.L., Seidelman, P.K. and Van Flandern, T.C.: 1975, IAU Coll. 26, Torùn, p. 223.