I have been using The Complete Glock Reference Guide for several years now. It contains page after page of invaluable information for Glock owners. It covers everything that you would expect: field stripping, disassembly, assembly, cleaning, and more. The most invaluable information for me has been the tables that detail the parts that all Glock models have in common. I used this to help build an inventory of spare parts for all my Glocks.
All of the information is presented in a very well organized way with plenty of white space and tables. There are tons of clear pictures to guide you through the procedures outlined in the book. It is also spiral bound which allows it to lay open easily on your work bench.
This is just the kind of book that a Tactical Handyman needs on his shelf.