Classifying Research documents


I am using Endnote X9 desktop, and collating journal papers for literature review. I have used a group (Project X) to containerise those project papers. Beneath Project X I have created sub folders to rank those papers according to the SJR system.

I need to further categorise these papers into sub groups, example, Historical, environmental, Material.

Can Endnote do this. Groups appear to be only two levels deep.

Thanks and regards

No, but I use keywords to categorize, So the keywords can be ProjectX-SJRcomponent-Historical and ProjectX-SJRcomponent-Environmental etc and one can then search or use these to create smart groups. 

Not as pretty, but pretty functional.