For some paper assignments, the only sources you'll be expected to consult are those assigned in class. These assignments will ask you to engage in some way with the assigned reading. For example, you might be asked to do a close reading of a poem for an English course or to test a theory using texts assigned in your Social Studies tutorial. For other assignments, you'll be asked to locate your own sources. Still other assignments may expect you to generate some of the sources yourself through lab research or interviews.
If you're writing in your concentration or in a discipline that has become familiar to you, you'll likely know what types of sources are considered reliable in that field. But when an assignment leaves the research process open and you're not familiar with the field, it can be challenging to figure out where to start. Between the holdings of books and journals in the Harvard libraries and the numerous electronic resources available through the library catalogs, you have access to an enormous variety of texts—literally millions of books and billions of files. In theory this is a great privilege: Scholars travel from around the world for access to Harvard's collections, and the Harvard librarians add to these collections with careful thought. But in practice, it can be paralyzing to start the process of figuring out which materials to consider.