@article{5815,
  author = {Piero Madau and J. Shull},
  title = {Cosmic Metal Production and the Contribution of QSO Absorption Systems to the Ionizing Background},
  year = {1996},
  journal = {The Astrophysical Journal},
  volume = {457},
  pages = {551},
  month = {Jan-02-1996},
  issn = {0004-637X},
  url = {http://adsabs.harvard.edu/full/1996ApJ...457..551M},
  doi = {10.1086/176751},
}