All the volumes of the shounen(boy's) light novel
BACCANO! can be seen in the official site for the anime here:
http://www.baccano.jp/gensaku/index.html
Click on the images for bigger covers.
They are organized from left to right according to publication date
meaning for now there are 9 volumes released, and the first BACCANO! light novel that got released is
BACCANO! The Rolling Bootlegs.