Gallo, L. C., Lehmann, I., Pietsch, W., Boller, T., Brinkmann, W., Friedrich, P., & Grupe, D. (2006). XMM–Newton observations of bright ROSAT selected active galactic nuclei with low intrinsic absorption. Monthly Notices of the Royal Astronomical Society, 365(2), 688-698. doi:10.1111/j.1365-2966.2005.09755.x.