I used these fabric bins with the cube book shelf.   I ordered three bins, for the nine cube book shelf. 

I ordered the design shown in the photo. the cubes hold all my hiking maps, and the book shelf all my hiking books. 

Only one small down size- the cubes are a syntheic fabric. I was expecting cotton or a cotton/poly blend.

On the upside, anyone buying this configuration for kids, it may be more stain resistant.