Summon is a tool used to search for books and journal articles at the same time. It will search the library catalog, plus all (or at least most) of the library's databases in a single search.
Summon is a good place to start if you don't have any idea where to begin looking or to do a preliminary search to get a general idea of what is available on a topic.
To get started with Summon, go the Mardigian Library home page, http://library.umd.umich.edu. Locate the Summon search box on the upper left hand side of your screen. Type your search terms into the available search box and click the "Go" button after the box.
Here is how the Summon search box appears on the home page.