Hassan, M. A., B. A. Korany, R. Misra, I. A. M. Issa, M. K. Ahmed, and A. F. A. El-Salam,
"X-Ray Spectral Study of AGN Sources Content in Some Deep Extragalactic XMM-Newton Fields",
Astrophysics and space science, vol. 339, issue 4, pp. 355–364, 2012.