For the Enthusiast

If you really get enthusiastic about Lua then the following resources might be interesting. Although you probably should do it on your own time rather than work time since this material is unlikely to make you more efficient at doing integration work.
The main academic paper about Lua discusses the philosophy behind its design:

R. Ierusalimschy, L. H. de Figueiredo, W. Celes,
Lua – an extensible extension language,
Software: Practice & Experience 26 #6 (1996) 635–652. [doi]

Brazilian Academy of Sciences, and the Brazilian Ministry of Science and Technology this paper was awarded the first prize (technological category) in the II Compaq Award for Research and Development in Computer Science in 1997. This award was a joint venture with Compaq Computer in Brazil.

For details on the implementation of Lua, see:

R. Ierusalimschy, L. H. de Figueiredo, W. Celes,
The implementation of Lua 5.0,
Journal of Universal Computer Science 11 #7 (2005) 1159–1176. [jucs · slides]

For a complete history of Lua till 2006, see:

R. Ierusalimschy, L. H. de Figueiredo, W. Celes,
The evolution of Lua,

Proceedings of ACM HOPL III (2007) 2-1–2-26. [doi · slides]

For a history of Lua till 2001, see:

R. Ierusalimschy, L. H. de Figueiredo, W. Celes,
The evolution of an extension language: a history of Lua,
Proceedings of V Brazilian Symposium on Programming Languages (2001) B-14–B-28. [ps]

The first paper describing Lua still has some historical interest:

L. H. de Figueiredo, R. Ierusalimschy, W. Celes,
The design and implementation of a language for extending applications,
Proceedings of XXI Brazilian Seminar on Software and Hardware (1994) 273–283. [ps]

For an early expository article, see:

L. H. de Figueiredo, R. Ierusalimschy, W. Celes,
Lua: an extensible embedded language,
Dr. Dobb’s Journal 21 #12 (Dec 1996) 26–33. [DDJ]