As for the book, I personally recommend it, but there are still some issues that could have been resolved with just a bit of research:
final project was not completed in '89, but in July '88 (p.63).
It seams that the info was just copied from this page: Alfa Romeo Spider / GTV 916
although no mention in the credits
Next, Proteo, was not the final design prototype for a GTV/Spider, but it was inspired by GTV/Spider, as they were made earlier, 2-3 years earlier (p.58).
Also this is not Enrico Fumia, it's Andrea De Adamich (p. 61):
not to mention the incorrect production numbers for year 1993, 1994 and 2004 (so far), correct are here:
Production Numbers » Yaroslav Bozhdynsky's Personal Website
also, there is an absolute lack of any information regarding the limited editions, except for ss.cup. Where comes the information about only a twenty GTV Elegant Limited Edition 2002? the German-market special editions that You mentioned are Edizione Elegante and Edizione Sportiva Spiders. "There would be three special-edition models[...]". There are almost 20 editions (p.133). Limited Editions » Yaroslav Bozhdynsky's Personal Website
Any sources for the I.DE.A. Alfa Romeo Portello Coupe mentioned on p.40?
The Vivace concepts were delibertely simillar to the 164 and styled by Diego Ottina.(p.51)
Any sources regarding the lack (or incompletion) of interior in 1994 at Motor Show (p.64)?
Bonnet is not made from carbon-fible but fibre-glass and weights around 30kg. (p.72)
Other then that good job.