Note that only publicly-traded U.S. companies file SEC EDGAR reports called 10-Ks.
Foreign companies which trade on the U.S. market (such as the New York Stock Exchange or Nasdaq) file SEC EDGAR reports called 20-Fs.
Foreign companies which trade on foreign markets do not file 20-F reports. But they do have to file annual reports in their home country. You may find these foreign annual reports in Mergent Online.
Private U.S. companies are NOT legally required to file 10-Ks or any annual report. And so they don't... for competitive reasons.
To find information on private companies, go to Company FAQs.
Aside from citing articles and books, have you ever wondered how to cite a company annual report or an industry report? The reality is, there is no "official" style for citing business sources. However, it is common practice to use adaptations of one of the following citation styles: the American Psychological Association (APA) Style or the Chicago Style. Whichever style you choose, use it consistently for the entire project/paper.