1. Champan, C. R.: 1986, Mem. Soc. Astr. Ital. 57, 103.
2. Clairemidi, S.: 1987, Earth, Moon, and Planets 38, 237.
3. Čelebonović, V.: 1986, Earth, Moon, and Planets 34, 59.
4. Čelebonović, V.: 1987b, in: Proc. of the 2nd workshop Astrophysics in Yugoslavia, M. S. Dimitrijević (ed.), published by the Astronomical Observatory, Beograd, Yugoslavia, p. 41.
5. Čelebonović, V.: 1988a, contributed paper at the 8th General Conference of the Cond. Matt. Div. of the Europ. Phys. Soc., Budapest (Hungary), April 6th–9th, 1988.