1. Aniol, R., Duerbeck, H. W., Seitter, W.C. and Tsvetkov, M.K. (1988), Messenger 52, 39.
2. Ambartsumian, V. A. (1969), Stars, Nebulae, Galaxies, Byurakan Symposium, Acad. Sci. Armenian SSR, Yerevan, p. 283.
3. Andrews, A.R. (1972), Bol. Obs. Tonantzintla y Tacubaya 6, No. 38, 179.
4. Chavushian, H. S. (1979), Thesis, Yerevan.
5. Duerbeck, H.W., and Tsvetkov, M.K. (1989), in Mirzoyan, L.V., Pettersen, B.R., and Tsvetkov, M.K. (eds.) (1989), Flare Stars in Star Clusters, Associations and Solar Vicinity, IAU Symposium 137 (to be published).