Making Sense of Change Management by Esther Cameron & Mike Green, published by Kogan Page.
This is a really useful all rounder book with all the theories you could ever want.

Change Management by Robert Paton & James Mc Calman published by Sage

Leading Change by John Kotter published by Ebury Press

How to Have Creative Ideas by Edward de Bono Published by Vermilion

The Dance of Change by Peter Senge published by Nicholas Brealy

How to Mind Map by Tony Buzan published by Thorsons

The Tipping Point by Malcolm Gladwell published by Abacus

Creating Contagious Commitment by Andrea Shapiro published by Strategy Perspective

The Inner Warrior by Beverley Stone published by Palgrave

Who Moved My Cheese? by Dr Spencer Johnson published by Vermilion

Leading in a Culture of Change by Michael Fullan published by Jossey-Bass