How about adding the ability to view citations and to open a selected document as primary interactions, such as below? Further options can of course be added over time. Personally I think having these options as text makes sense, since text blends with text whereas icons or buttons stand out and can become clutter.
If the user chooses ‘Citation Links’ (or similar phrasing), the following happens: The Catalog disappears and a list of all the documents referenced by the selected document appears on the left and every document in the user’s Library appears on the right:
The user can now choose to tap on any document, in any column, for it to open and become the central document with abstract displayed. To leave this view and to go back to the Library the user can tap the ‘Library’ button/text.
The titles of the columns; ‘References’ and ‘Cited by’ might serve as points for pop-up menu options to tear the lists off so that they can remain for the user while the user continues exploring references.