Ducati books
For a good pictoral history there is "Ducati Superbikes" by Paolo Conti.It covers the 851,888 and 916.
Another good one is "Ducati 4 valve twins" by Mick Walker.
The best one tho,is "Ducati Desmoquatro Super bikes" by Ian Falloon.Loads of info,production runs,model changes etc.