The current version is v2013.01.13a (single-column format, changes). The corresponding bibtex may be found here.
Older versions are available as well:
New releases should appear three to four times a year, give or take. This work is covered by the terms of the Creative Commons Attribution-Share Alike 3.0 United States license.
If you would like a dead-tree copy, please feel free to use any of a number of internet-accessible printing services. If you would like a fancy dead-tree copy, there is some appropriate artwork for front and back covers, courtesy of Melissa Broussard.
Contributions are welcome, and to that end, a public git tree
may be found at
This git tree also provides an up-to-date version for those who are too
impatient to wait for the next release.