Corporate reports for over 8,500 companies- 10K, 10Q, 8Q, Schedule 13 G files, Letters to Stockholders, Prospecti, etc. Also SEC Digest, Press Releases, Congressional Testimony and Special Studies.
Use the search techniques you learned about for other databases here.
Note: Google does not support nesting (parentheses) or truncation (*).
It does something called automatic stemming, which is sort of like truncation, but takes the control away from you and isn't as exact.
Note that limiting your search to articles where your words occur in the title is a kind of field searching, and can vastly narrow your searches and increase the relevance.