The Cinema 4D library!
But honestly... You can make a book in a minute.
Create a cube with 3 divisions, squash it down(y), "c", move the cuts towards the edges, bevel one side and on the other extrude the cover polys(from the divisions)a bit. Select front, side and back polygons and create a selection.
Unwrap UVs using cube or box(1/2) projection. Align UVs of the selection and add a material with something like this:

For more covers google " book covers"
For the rest, the sides with the pages assign a different material and use a tiles, gradient or something that repeats.
This is the fastest way. you could also subD model it in about the same time if you want.
Mograph Cloner--->shelf
Variation Shader--->colors&covers
There you go. A quick book in 5 minutes.