Try using these in the OneSearch, Academic Search Complete, or other databases.
These organizations produce research on a large number of issues, most of which they make freely available online. They are biased; they are trying to influence policy. So you should be aware of their orientation and take it into account when you quote their reports. Use the site's search box, or browse the section called "reports," "research" or something similar.
This group of researchers from UC Berkeley and Harvard are challenging assumptions about inequality in the U.S.