Alphanumerically sort Backgrounds in the Library

I am trying to export the background images of a section of my slides.  I know the background numbers of the first and last slides of the section. 

However, the backgrounds are listed in lexical order, not alphanumerical order.

I need to be able to alphanumerically sort the backgrounds so I can select ALL the backgrounds (at the same time) of the section that I want to export.