The official handbook on the Subversion revision control system. If you've never used it before, start here. It's free to read online and download for later (HTML, PDF, DocBook XML). Or you can buy it from O'Reilly for good karma.
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A Creative Commons handbook that teaches the legal, social, and technical aspects of open data. Teaches not only what you can do with an open data set, but how to go about getting datasets opened to analysis. If you're looking for a hands-on nitty-gritty book about mining open data, however, this isn't it.
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A free handbook for journalists that describes how to verify and vet information from socialmedia sources. Written by journalists from the BBC, Storyful, ABC, Digital First Media, and other news organizations. Free to download as a PDF, ePub, or kindle ebook. Available in English, Greek, French, Portuguese, Spanish, Arabic, Russian, Turkish, Coatian, and Italian.