My favourites include (Lennard) Zinn and the Art of Road Bike Maintenance (plus there's a MTB version), and Jim Langley's Complete Guide to Bicycle Maintenance and Repair.
There is an online copy of Barnett's at bikeforums.net.
Also, Effective Cycling by John Forester (6th Ed.). There is a pretty good section on maintenance. Mr. Forester has very specific ideas about some cycling issues especially where to ride (road v. bike path). But , hey nothing wrong about being passionate about what you believe in.
Also, the Zinn books are very good.
Finally, if you cultivate a good relationship with your LBS they should be willing to answer your questions.