The following are various resources which will help you locate documents for publicly traded companies that you are interested in researching.
Google Search of the Company's Website for Investor Relations. The documents the company has filed will be listed here. You may also find annual reports (which is not a required S.E.C. document), news releases, conference calls, presentations to analysts and corporate social responsibility reports.
Bloomberg Terminal-Ticker Symbol>EQUITY<CF>GO. Example: AAPL<EQUITY><CF><GO>