I’ve done stacks of books before. This time I used a different technique to mitigate the reflection of the flash. Before I explain, note that the books were standing vertical on the shelf; I have rotated the final image 90 degrees. I did not have my diffuser or a bounce handy for the flash. I angled the camera from the right about 10 degrees. In post-processing, I corrected the perspective in PTLens. I had the aperture set at f/8, so I had some depth of field to work with. I’m finding PTLens to come in handy for more than just correcting wide angles.