Where can I learn more about TOC?

The best source of information on TOC is:

Dettmer, William H. (1997). Goldratt's Theory of Constraints: A Systems Approach to Continuous Improvement. Milwaukee: ASQC Press

Another source from 'the man' (and perhaps the first published reference on TOC):

Goldratt, Eliyahu M. (1990). What is this thing called Theory of Constraints and how should it be implemented? Croton-on-Hudson: North River Press