Ragusa A State of Deference
This is a information packed book on the history of one of the most interesting Midevel cities in the world. Like most non-fiction accounts it is slow reading, but contains many footnotes, illistrations and a few photographs. It incluses a time line and a good index.
If you are serious about knowing all about Ragusa and Dubrovnik this is a great book.
There is, however, no chapter on the maratime trade and commerse, rather the information is spread througout the book.