The main journal article of reference for this data set is:
Nordhaus, W.D. 2005. Geography and macroeconomics: New data and new findings. Proceedings of the National Academy of Sciences of the United States of America (PNAS), 103(10): 3510-3517. http://dx.doi.org/10.1073/pnas.0509842103.
In addition to this article, a number of other documents developed by the Yale G-ECON team may be useful to users of this data set: