You should submit an annotated bibliography of at least four sources to be used in the refutation speech. The annotated bibliography should properly document your sources, summarize their main points, and explain how they will be useful in preparing your speech. At least two of the sources should be academic (e.g., books and academic journals), and all the sources should be credible (e.g., established media [i.e. not Buzzfeed], organizations, or think tanks).
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.