Lambda Calculus

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:

Clemens Grelk's.

There are introductory online courses on lambda calculus. Here are a few pointers:

Chris Barker's (including an interactive Javascript evaluator)
Jim Larson's.
Ralph Loader's.
L. Allison.