1. Blanco, V. M.: 1982,Publ. Astron. Soc. Pacific 94, 201.
2. Brown, G. S.: 1978, in R. M. West and L. Heudier (eds.),Modern Techniques in Astronomical Photography, European Southern Observatory, p. 169.
3. Buonanno, R., Corsi, C. E., De Biase, G. A., and Ferraro, I.: in G. Sedmak, M. Capaccioli, and R. J. Allen (eds.),Image Processing in Astronomy, Trieste, p. 354.
4. Buonanno, R., Corsi, C. E., and Fusi Pecci, F.: 1981a,Monthly Notices Roy. Astron. Soc. 196, 435.
5. Buonanno, R., Castellani, V., Corsi, C. E., and Fusi Pecci, F.: 1981b,Astron. Astrophys. 101, 1.