Use keywords to make a concise search query and avoid full sentences or too many words - this will yield better results :).
For example, African Americans and jazz.
Combine the name of the group you are studying with the aspect you want to find out about. For example,
African Americans AND (combine with one of the following):
Newspapers, magazines, and scholarly journals published by and about various racial and ethnic groups in the United States.
Background information from general and subject encyclopedias.
Scholarly journals, professional journals, reports and magazines in the social sciences, the humanities, and general sciences.
Full content from 1945 to 2014 from the prominent mass-market magazine targeted to an African-American readership.
Full content from the entertainment and culture magazine focused on African-American entertainment and culture.