Kollmeier, J. A., et al. 2014, The Photon Underproduction Crisis, ApJL, 789, L32
Haardt, F., & Madau, P. 2012, Radiative transfer in a clumpy universe: IV. New synthesis models of the cosmic UV/X-ray background, ApJ, 746, 125
Madau, P., & Haardt, F. 2009, HeII absorption and the sawtooth spectrum of the cosmic far-UV background, ApJL, 693, L100
Haehnelt, M. G., Madau, P., Kudritzki, R., & Haardt, F. 2001, An ionizing ultraviolet background dominated by massive stars, ApJL, 549, L151
Madau, P., Haardt, F., & Rees, M. J. 1999, Radiative transfer in a clumpy universe: III. The nature of cosmological ionizing sources, ApJ, 514, 648
Haardt, F., & Madau, P. 1996, Radiative transfer in a clumpy universe: II. The ultraviolet extragalactic background, ApJ, 461, 20
Madau, P. 1995, Radiative transfer in a clumpy universe: The colors of high redshift galaxies, ApJ, 441, 18
Madau, P., & Meiksin, A. 1994, The HeII Lyman-alpha opacity of the universe, ApJL, 433, L53
Madau, P., Ghisellini, G., & Fabian, A. C. 1994, The unified Seyfert scheme and the origin of the cosmic X-ray background, MNRAS, 270, L17
Madau, P. 1992, The contribution of quasars to the ultraviolet extragalactic background, ApJL, 389, L1
Madau, P. 1991, QSO absorption systems and the origin of the ionizing background at high redshift, ApJL, 376, L33