D. Nicholls, M. Dopita, H. Jerjen, and G. Meurer. (2011)cite arxiv:1107.3898Comment: 13 figures, 3 table. Accepted for publication in The Astronomical Journal.
V. Bromm, and N. Yoshida. (2011)cite arxiv:1102.4638
Comment: 75 pages, 14 figures, draft version for 2011 Annual Reviews of
Astronomy and Astrophysics.