Articles about your nonprofit and the problem to be solved by the nonprofit are often topics for newspaper, magazine, blog posts and other online popular media. Consider news articles written by reporters and editorials written by subject experts.
Many online sources can have similar elements and generically seem to be relevant articles. Be sure to evaluate the credibility and authority of the articles you find in internet search results.
Using a database accessible from the KU Libraries' webpage can help you find relevant articles.
In addition to having good ratings from watchdog groups (see Nonprofits tab), look for announcements about other awards that could help highlight the organizations effectiveness and impact. Below are a couple of examples. There may be others!