If you ask around, you'll find that there is one workshop manual
overwhelmingly recommended for owners of contemporary Ducatis: LT
Snyder's
Ducati Desmodue/Desmotre Maintenance and Modification Guide

It's spiral-bound, practical in content and with lots of photos.

You can order one for the 2v desmodue (900ss/907ie/etc) and 3v
desmotre (ST3, etc) motors, or a different one for the 4-valve heads,
from http://www.desmotimes.com/

Mine showed up extremely quickly after ordering it, and you'll also
find that LT stocks parts, tools and other goodies in his online
store.