The book is, Encyclopedia Of Spirits: The Ultimate Guide To The Magic Of Fairies, Genies, Demons, Ghosts, Gods & Goddesses by Judika Illes.
The title of the book is misleading. This book is almost entirely on pagan gods. The entries are not detailed and are only basic or rudimentary with regard to the information presented. The writing style of the author is somewhat cheesy and much of the information has seemingly been made up in the typical Wiccan-fashion.
On a scale of 1 to 10, with 1 being the lowest and 10 being the highest, I give this book a 1. I would not recommend it.