There are an abundance of self defence books out there for sale, some are good and some are
absolute rubbish.

These are three of my favourite self defence books.  I recommend reading all three simply
because these books look at self defence from slightly different perspectives.  So by reading all
three you will get a good insight into realistic self protection.  
This book is by the world's leading authority on pressure point
fighting, Grandmaster George Dillman 9th Dan.

This book covers the psychological affects of being attacked as
well as how to use your attacker's anatomical weaknesses to
defeat him/her.

Perfect for business persons, law enforcement personnel, men
and women. Contains 600 photos and diagrams, and 264 pages of
step by step instruction.
This book is by Geoff Thompson, a 6th Dan in Japanese karate

This book teaches simple precautionary measures that
everyone can take to make themselves less vulnerable to
attack, and explains what victims should do when confronted
by an assailant. Geoff interviews murderers, rapists and
muggers who reveal why they target certain people.
This book is by Peter Consterdine, 8th Dan Karate.

This book covers a broad range of self defence topics.  
From protection on the street to protection in your home.
It also covers the Law as it relates to self defence.