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How Git Works (zine by Julia Evans)
(wizardzines.com)
Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency.
Resources
Rules
Git Logo by Jason Long is licensed under the Creative Commons Attribution 3.0 Unported License.
I was going to say there are about a gazillion free Git tutorials so this seems like a strange thing to charge quite a lot of money for. But it does look very well done.
I understand the "why would I pay for this" reaction. I think crowdsourcing is a better approach for these kinds of content. Once you reach certain level of financial commitment from the crowd, you can give away the PDF and sell the print copy.