By Chris Garrard, author of Geoprocessing with Python
In order to effectively work with coordinate systems you need to understand why there are so many of them in the first place and how to select an appropriate one for your purposes. In this article, based on my book Geoprocessing with Python, I give you some background information about spatial reference systems.
By Warren D. Sande and Carter Sande
This article is taken from the book Hello World! Computer Programming for Kids and Other Beginners
Getting Started (PDF)