Lonely Planet

http://www.lonelyplanet.com/destinations/europe/italy/

Rough Guides

http://travel.roughguides.com/roughguides.html

Footprint

http://www.footprintbooks.com

Alastair Sawdays

http://www.specialplacestostay.com/titles/it/index.html

Fodors Guides

http://www.fodors.com/

Frommor's Guides

http://www.frommers.com/destinations/italy/

Amazon.com

http://www.amazon.com