The Hamburg/RASS Catalogue of optical identifications N. Bade, D. Engels, W. Voges, V. Beckmann, Th. Boller, L. Cordis, M. Dahlem, J. Englhauser, K. Molthagen, P. Nass et al. (2 more) Astron. Astrophys. Suppl. Ser., 127 2 (1998) 145-152 Published online: 15 January 1998 DOI: 10.1051/aas:1998339