Stirling Engine References 
This list is a strictly personal listing of books that I have found helpful and instructive with regard to Stirling Engines. I make no claim as to completeness or usefulness to others.
Address/ Comments
Senft, James:  Introduction to Stirling Engines Moriya Press PO Box 384 
River Falls, WI 54022
Senft, James Introduction to Low Temperature Differential Stirling Engines Moriya Press
Senft, James Ringbom Stirling Engines Oxford University Press Most Booksellers
Senft, James Moriya, A Stirling Powered Fan, set of plans Moriya Press PO Box 384 
River Falls, WI 54022
Various Steam and Stirling Engines You Can Build: Vols 1 & 2 Village Press see below
Rizzo, James The Stirling Engine Handbook Most booksellers
Kolin, Ivo History of Heat Engines Moriya Press as above
Books on Stirling engines as well as other books of interest to model engineers can be found on the web at Bailey Craftsman's Supply, Lindsay Books, and the Village Press (which publishes Home Shop Machinist, Live Steam, and Machinist's Workshop). 

Bob Bailey has also produced a very interesting video on Stirling engines, which I highly recommend.

The usual disclaimer applies: I have no association with these firms other than as a satisfied customer.