EDGAR

EDGAR (Electronic Data Gathering, Analysis, and Retrieval) is the Securities and Exchange Commission's free public database of company filings. Every 10-K, 10-Q, and 8-K a U.S. public company is required to file lands here, and anyone can search it and read the filings for free.

Because it's the primary source, the filing exactly as the company submitted it to the regulator, it's the one place a number quoted anywhere else can always be checked against.