Look up the people, organizations, and agencies as authors

Materials that were written or produced by them either at the time of the event or later will, in most cases, be primary sources. Examples:

In any of the catalogs, look up individual names as personal author or author.

sanger, margaret
pankhurst, christabel

Look up group names or organizations as corporate author or author.

United States Department of Justice retrieves a collection of pamphlets they issued

congress of racial equality retrieves the Congress or Racial Equality (CORE) papers