NY: Schirmer Books, 1998

John Platt's excellent book is now out of print but a must get for hard core fans.  It covers there full history with emphasis on the Gears sessions.   John was a music journalist in the UK in the mid-late 60's and personally new each of them.  He is still in close contact with Jack & Ginger. 

The book is well researched and clears up the confusion over the Gears sessions dates.  The pre-Cream and early days are also well covered.