Sonic the Hedgehog Classic Style Guide
From Sonic Retro
Sonic the Hedgehog Classic Style Guide is a book intended for use by merchandise producers used in the 2010s. It contains modernized versions of past American and Japanese art assets. Following Sonic art assets DVD, it is the first core guide created with a focus on "classic" Sonic artwork, as modern artwork was used for its counterpart.
Scans and digital versions
Digital version