Discover@MU provides one search covering MOST (but not all) of the content the Libraries provide.
Once you have search results on the screen, you can tailor these by using limits in the left sidebar or by using the drop-down menus in the search box to make your search more precise.
The default is to search just materials immediately available at MU, but untick the box in the left sidebar to extend your search to things we can get via interlibrary loan.
The results sort by relevancy (i.e. how often your search terms appear) but you can resort by date.
Remember basic search techniques:
Library catalogs provide an inventory of books held by libraries. Typically they do not search or provide the full text of books or other materials online. Google Book Search or the Hathi Trust search the full text of books, but often can display only portions of the text due to copyright restrictions. Follow the "find in a library" links in these to locate the physical book in a library.
Organizations or institutions monitoring ongoing issues or preserving the past are often good starting places for research.