Sandra Billington & Miranda Green 
The Concept of the Goddess [PDF ebook] 

The Concept of the Goddess explores the function and nature of goddesses and their cults in many cultures, including:
* Celtic
* Roman
* Norse
* Caucasian
* Japanese traditions.
The contributors explore the reasons for the existence of so many goddesses in the mythology of patriarchal societies and show that goddesses have also assumed more masculine roles, with war, hunting and sovereignty being equally important aspects of their cults.