I needed a book light too and went with the Reading Light with Clip - Deaunbr USB Rechargeable Book Lights. It has a huge clamp which fits most places and is dimmable AND rechargeable. A great purchase that has a long battery life!
Energizer Clip on Book Light for Reading in Bed, LED Reading Light for Books and Kindles, 25 Hour Run Time, Kindle & Book Reading Lamp (Batteries Included), White. This is what I ordered for my boys at Christmas time. These clip on to the book and provide a lot of light.