Primary sources enable the researcher to get as close as close a view as possible to what happened during an historical event or time period and how it was perceived by the participants and observers. Historians use primary sources as evidence to make new observations and interpretations of an event, place, era, or other historical phenomena.
The following are generally considered primary sources:
Diaries, journals, speeches, interviews, letters, memos, manuscripts, and other papers in which individuals describe events in which they were participants or observers.
Memoirs and autobiographies. These are generally less reliable since they are usually written long after events occurred and may be distorted by bias, dimming memory, or the revised perspective that may come with hindsight.
Records of organizations and agencies of government. The minutes, reports, correspondence, etc. of an organization or agency serve as an ongoing record of the activity and thinking of that organization or agency. Many kinds of records (births, deaths, marriages; permits and licenses issued; census data; etc.) document conditions in society.
Published materials (books & newspaper, magazine, or journal articles) written at the time about a particular event. While these are sometimes accounts by participants, in most cases they are written by journalists or other observers. The important thing is to distinguish between material written at the time of an event as a kind of report, and material written much later, as historical analysis.
Photographs, audio recordings, video recordings, drawings, paintings, or political cartoons, documenting what happened.
Artifacts of all kinds: physical objects, buildings, furniture, tools, appliances, household items, clothing, toys.
If you are attempting to find evidence documenting the mentality or psychology of a time, or of a group (evidence of a worldview, a set of attitudes, or the popular understanding of an event or condition), the most obvious source is public opinion polls taken at the time. Since these are generally very limited in availability and in what they reveal, however, it is also possible to make use of ideas and images conveyed in the mass media, and even in literature, film, popular fiction, self-help literature, textbooks, etc.
Again, the point is to use sources written or produced at the time as evidence of how people were thinking.