A view from "the other side" which I really enjoyed was "Torpedoes In the Gulf - Galveston and the U-Boats 1942-1943" by Melanie Wiggins. (Amazon link:
http://www.amazon.com/Torpedoes-Gulf...9373167&sr=8-2)
Of course, being a Texan, my view is a bit biased but I really enjoyed seeing how a community responded to the U-boat threat. There was also a fair bit about the operational history of the boats operating here just off the Gulf of Mexico. A nice quick read that gives you a real sense of what it was like living in the shadow of the Grey Wolves.