You can view the hierarchy of the unloaded references in your scene using the Preview unloaded content option. If needed, you can then quickly reload the reference by selecting Reload from the Reference menu.
To see the contents of an unloaded reference
-click the unloaded reference, and then select Reference > Preview unloaded content from the menu that appears.
The Outliner displays the hierarchy of the unloaded reference.
-click the unloaded reference again and select one of the following options: