The *(term) for the mathematically formalized theory of abstractions. Well, it's recursive, lexically-scoped theory of functions. And it's not just one theory; there are variations.

The usual reference for it is a 1984 book by Barendregt. See logic and functional _(Programming Languages), as well as lambda calculus as a virtual machine - the _(Lambda VM).

A few bibliographies:
<ul>
<li><A HREF ="http://www.informatik.uni-kiel.de/~cg/bib/bookshelf/LAMBDA-Calculus.html">Clemens Grelk's</a>.
</ul>

There are introductory online courses on lambda calculus. Here are a few pointers:
<ul>
<li><A HREF="http://www.jetcafe.org/~jim/lambda.html">Jim Larson's</a>.
<li><A HREF= "http://www.dcs.ed.ac.uk/lfcsreps/EXPORT/98/ECS-LFCS-98-381/index.html">Ralph Loader's</a>.
<li><A HREF="http://www.cs.monash.edu.au/~lloyd/tildeFP/Lambda/">L. Allison</a>.
</ul>

See also _(Epsilon Calculus).