Primary: You will use 2 primary sources; which they are will depend on the prompt you choose Secondary: You will use at least 4 secondary, or scholarly, sources in support of your claims. These may include articles and books. A scholarly article is one that has appeared in a peer-reviewed academic journal.
All applicants go through a series of tests that check their level of English and knowledge of formatting styles. The applicant is also required to present a sample of writing to the Evaluation Department. If you wish to find out more about the procedure, check out the whole process.