1. Lynga, G.: Catalogue of open cluster data, 5th edition, distributed on magnetic tape or microfiche by Centre de Données Stellaires, Strasbourg, or by Data Center A, NASA (1987).
2. Int. Astron. Union Symp.;R. F. Webbink,1985
3. Zinn, R.: J. R. Astron. Soc. Canada 84 (1990) 89.
4. Astron. Soc. Pacific Conf. Ser.;J.E. Hesser,1993
5. Int. Astron. Union Symp.;J.E. Hesser,1995