Tozzi, P., Gilli, R., Mainieri, V., Norman, C., Risaliti, G., Rosati, P., Bergeron, J., Borgani, S., Giacconi, R., Hasinger, G., Nonino, M., Streblyanska, A., Szokoly, G., Wang, J. X., & Zheng, W. (2006). X-ray spectral properties of active galactic nuclei in the Chandra deep field south. Astronomy & Astrophysics, 451(2), 457-474. doi:10.1051/0004-6361:20042592.