There is a more recent work published by Willam Hovey Smith entitled Crossbow Hunting. It's front cover proudly displays a wary Bill Troubridge beating the bush with his trusty Excalibur. It is all inclusive of the modern crossbows and is not only detailed, but very well written. That work can be purchased at:

http://www.amazon.com/Crossbow-Hunting-William-Hovey-Smith/dp/0811733114