Except for ABI-Inform, the databases below are also included in Library One Search.
The benefit to searching them individually is that each has its own subject vocabulary to express certain concepts, as well as different categories to limit by specific to the discipline.
Also, you will have a smaller set of results, so it may be easier to figure out what it is available and how it is being described.
PsycInfo has articles pertaining to ethnic studies, but the term "ethnic studies" is not a subject term used in this psychology database. "Ethnic studies" appears in the title, but not in the subject headings. The terms boxed in red are some of the terms of what indexers use for this concept in this database: "educational programs" and "racial and ethnic socialization."
We can see here, in the full record, that "ethnic studies" is also an author-supplied keyword.