There are two
Dattari volumes available these days.
The Forni reprint is a reprint of the original 1901
Dattari catalogue. It is a true
catalogue, written in
Italian, but easy to follow if you have rudimentary Latin skills (e.g. sinister or s.=left, etc.)
The new, often - called "Dattari/Savio" is a limited-issue volume containing plates of rubbings that
Dattari made of
his collection. It illustrates all the coins in the 1901
catalogue, plus several hundred more. It is not really a
catalogue, it is just plates; although each coin rubbing is numbered so you can use it like a
catalogue with patience. This volume is a new, high production value, limited edition and is more expensive than the Forni reprint of the 1901
catalogue.