1. Battinelli, P. and Capuzzo-Dolcetta, R.: 1989,Astrophys. J. (in press).
2. Janes, K. and Adler, D.: 1982,Astrophys. J. Suppl. 49, 425.
3. Lynga, G.: 1983,Catalogue of Open Cluster Data, 3rd ed., Stellar Data Centre, Observatoire de Strasbourg, France.
4. Pandey, A. K. and Mahra, H. S.: 1986,Astrophys. Space Sci. 126, 167.