O. Post. (2007)cite arxiv:0712.1507Comment: 24 pages, extended version of a lecture held at the EPF Lausanne, some references added and typos corrected.
S. Parameswaran, R. Roy, and S. Sondhi. (2013)cite arxiv:1302.6606Comment: 30 pages, 4 figures; review submitted to topical issue of Comptes Rendus Physique devoted to topological insulators and Dirac matter. Pre-publication version; comments are invited.
S. Donaldson. (1999)cite arxiv:math/9911248Comment: 16 pages. Published copy, also available at http://www.maths.warwick.ac.uk/gt/GTMon2/paper4.abs.html.