In addition to all of the statistical data you'll be looking at, you'll need scholarly (and often peer-reviewed) journal articles. These can be difficult to find, especially if you rely on the open web. Instead, start in some of these library resources to find journal articles. If you find a record for something that isn't available in full text, you can use Interlibrary Loan to request it.

Citing your sources properly -- yes, even the charts and graphs you reuse from other sources, and the statistics you quote -- is important and required.

Purdue University's OWL Writing Lab Citation resources are the best ones out there on the web. Generally, Business & Economics courses require that you use APA citation style. Detailed information on both in-text references and "works cited" pages is available here.