Advanced Search is accessible from the 'Advanced Search' link above the basic search box at the top of each page.
Advanced Search allows you to limit your initial search by content type(s)—Articles, Images, Games and Videos—and by subject(s). Enter a search term in the search box, select any limiters, and then press Enter or click the 'Search' button. Aside from the limiting options, the Advanced Search box handles search terms and Boolean searches in the same way as the basic search and it also allows blank searches along with a filter. You can also Search by Standards by clicking the link above the Search button.