Para provar que nem tudo o que interessa tem que ser pago, aí estão 10 livros gratuitos sobre software open-source.

1 - Linux Starter Pack
2 - The Easiest Linux Guide You'll Ever Read
3 - Ubuntu Pocket Reference and Guide
4 - Producing Open Source Software - How to Run a Successful Free Software Project
5 - tuXlabs Cookbook
6 - Free Culture
7 - The Blender Basics
8 - Free and Open Source Software for Development
9 - LPI 101 and 102 study notes
10 - The Cathedral and the Bazaar

Fonte: Bestlinux