A few weeks ago the Pix'n Love Publishing release a book about Sonic The Hedgehog. It has been approved by Sega and it's the first time for a book about Sonic according to the publisher. It's only available in French for the moment but it should be release in english next month.
The book is devided in three parts: the first one is about the story of Sega and Sonic games developement, the second one is a listing of all the Sonic game ever done and the last part is about the characters. The book is beautiful with full of images, and the content very precise and interesting. There's also an interview of Yuji Naka (the programer of the first Sonic), Takashi Iizuka (in charge of the current Sonic games at Sega) and Naoto Oshima (the designer of Sonic).