Pocket Valve Big Twins 1915-1929. An Identification and Restoration Guide - Steve Slocombe
Spiral Bound Restoration Book. Bout 3/4" thick.
You definitely should have one of these on your desk.
The Machines by Year (photo Identification)
Frames and siderails
Seats and seat posts
Handlebars and Controls
Tool and Battery Boxes
Tanks and lines
Wheels/Hubs and Brakes
Electrical and Ignition
Lights and horns