reference of an assembly in another assembly

Hi,

I am trying to clean up some of my solidworks files. Before deleting some files, I need to check if the files is referenced in an assembly.

When we open a part, we can see if this part had been referenced in an assembly.

However, how can we check if an assembly is referenced in another assembly?

when I click <>, <> in an assembly, it only shows the parts referenced in that assembly.

thank you

Linh-Chi

SolidworksAssemblies