To locate the source of a shared collection, click on any image to bring it into the Detail View. At the Very bottom of the Media Information panel, you'll see a field called Link to Source. Click on the link below to view the source where it originates from.
IIIF Activity Stream
If your collections are public and permission in the Collection Manager allows for the collection to be shared, another LUNA Admin can add your collection to their own instance and vice versa, by using the IIIF Activity Stream URL. To locate a IIIF Activity Stream in the Viewer for a collection you want to add to your own instance, select a collection and then click Share from the menu above (you can do this from the Collections page, Browse All page or Detail View page when in context of a single collection).
Click the arrow next to IIIF Activity Stream to expose the IIIF Activity Stream URL. Copy the URL and follow the instructions on adding Shared Collections to your own LUNA instance.