For historical information that isn't a primary source, you can use secondary sources. Secondary sources are works that analyze, assess or interpret an historical event, era, or phenomenon. Unlike primary sources, secondary sources are written well after the historical event/era/phenomenon takes place. For example, a book published in 2020 analyzing the effects of the Civil War on American society is considered a secondary source.
Secondary sources can be articles, books, videos, etc. The databases below are the ones best suited for finding information on historical topics.