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Summary
The official book about the Lua language, giving a solid base for any programmer who wants to use Lua. Authored by Roberto Ierusalimschy, the chief architect of the language, it covers all aspects of Lua 5.0---from the basics to its API with C---explaining how to make good use of its features and giving numerous code examples. Programming in Lua is targeted at people with some programming background, but does not assume any prior knowledge about Lua or other scripting languages.

The author maintains a support page for the book here.