This is a type of prototype.
It is a copy of a "style Guide 1994" for Sonic. It has small versions of air brushed art pieces that served as the ORIGINAL art for several items produced later. In the industry, one art piece can be created, and then given several uses, or cut apart to create several different items. In this case, you can see Spinball art from 1994, the Sonic 3 special stage 'planet' & a seldom-seen ski jump Sonic in a snow scene.
A style guide gathers all the art of the time before it is actually used, into a book. The circle tabs there on the edge say "style model sheets" and "logotypes". This is a very interesting find, even if it is an exact copy of a 1 of a kind style guide book.