The Hamburg/RASS Catalogue of optical identifications - Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sourcesF.-J. Zickgraf, D. Engels, H.-J. Hagen, D. Reimers and W. VogesA&A, 406 2 (2003) 535-553DOI: https://doi.org/10.1051/0004-6361:20030679
