Neapolitan/Venetian/Roman - Substyles of Italian Music

Can someone tell me what are some of the trademarks of these sub-styles of Italian music? And is there a book where I can find about these?

All that I can really suggest, and I'm not a master of the topic, is that those styles refer to the baroque era substyles of italian music.

Now that I've just restated the obvious, I'll go into what I do know. The Venetian style was exemplified by Vivaldi- and is more instrumental in nature, the Neopolitan Alessandro Scarlatti- more vocal in nature, and I suspect that the Roman style refers to those composers still writing in older styles like Palestrina.

When looking it up on various sites (cited below), it seems that the styles are also inherent in how opera plots were made: Venetian operas had mythological plots, Neopolitan operas were much more politically based, or at least more historical, and the Roman style was that of the Sacred Opera.

Alessandro Scarlatti: life and work, in Rome and Naples

Baroque Era - Vocal

Hope that was somewhat helpful. I suspect that if you wanted more info on these subjects searching for a book on Scarlatti or Vivaldi would be helpful.