Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.
Companies should report their financial performance in their annual financial reports, and these are the best places to find this information.
For companies that file with the SEC, this information can be found within their "Form 10-K" filings. You can often find these documents by searching for "Company 10-k", or they can be found through the SEC's EDGAR search.