Cross-correlation of the 2XMMi catalogue with Data Release 7 of the Sloan Digital Sky Survey F.-X. Pineau, C. Motch, F. Carrera, R. Della Ceca, S. Derrière, L. Michel, A. Schwope and M. G. Watson A&A, 527 (2011) A126 Published online: 09 February 2011 DOI: 10.1051/0004-6361/201015141