Spectroscopic identifications of Spitzer sources in the SWIRE/XMM-Newton/ELAIS-S1 field: a large fraction of active galactic nucleus with high F(24 {mu}m)/F(R) ratio

Spectroscopic identifications of Spitzer sources in the SWIRE/XMM-Newton/ELAIS-S1 field: a large fraction of active galactic nucleus with high F(24 {mu}m)/F(R) ratio