Lusso, E., Comastri, A., Vignali, C., Zamorani, G., Brusa, M., Gilli, R., et al. (2010). The X-ray to optical-UV luminosity ratio of X-ray selected type 1 AGN in XMM-COSMOS. Astronomy & Astrophysics, 512: A34 (14pp). doi:10.1051/0004-6361/200913298.