1. de Vegt, C. and Gehlich, U.K.: 1981, Astron. Astrophys. 101, 191
2. Fanselow, J.L., Sovers, C.J., Thomas, J.B., Bletzacker, F.R., Kearns, T.J., Purcell, Jr., G.H., Rogstad, D.H., Skjerve, L.J. and Young, L.E.: 1981, in Reference Coordinate Systems for Earth Dynamics, eds. E.M. Gaposchkin and B. Kolaczek, D. Reidel, Dordrecht, p.351
3. Høg, E. and von der Heide, J.: 1976, Perth 70. A Catalogue of Positions of 24 900 Stars, Hamburger Sternwarte, 334 pp
4. Schwan, H.: 1983, private communication
5. Walter, H.G. and West, R.M.: 1980, Astron. Astrophys. 86, 1