Today while trying to figure out how to use two graphics packages, I discovered that people without internet connections apparently don't deserve documentation. I am still ignorant of how to rotate shapes in both Inkscape and Xara LX (two programs that will never ever challenge any real vector graphics software) assuming it's even possible, because the documentation is provided as a web link.
A guide to Drupal APIs.
A guide to developing themes for drupal.
Drupal Module Developers' Guide
Contributors' Guide: Developing for Drupal
Drupal Advanced User's Guide