@article{8ed481a7c2124911bee4fb823eed4617,
title = "Very different X-ray to optical column density ratios in gamma-ray burst afterglows: ionisation in GRB environments",
author = "D. Watson and J. Hjorth and J. Fynbo and P. Jakobsson and S. Foley and J. Sollerman and R.A.M.J. Wijers",
note = "Original article can be found at: http://www.iop.org/EJ/journal/apjl Copyright American Astronomical Society DOI: 10.1086/518310 [Full text of this article is not available in the UHRA]",
year = "2007",
doi = "10.1086/518310",
language = "English",
volume = "660",
journal = "The Astrophysical Journal",
issn = "0004-637X",
publisher = "American Astronomical Society",
number = "2",
}