Secondary Sources are materials written after the event. Examples:
Primary Sources are the direct historic article or event being examined, or contemporary materials about the event/film. Examples:
NOTE: Whether a a source is primary or secondary depends on the topic being studied. Example:
Language has changed over the centuries, and it is often difficult to speak like - and think like - our ancestors, even in the 20th century.
Words like college, race, gender meant different things.
Most primary source databases will have "thematic" filters to get you started. Before keyword searching, start there. See what curated documents come up. From those documents, see what terminology is being used by contemporaries.
Begin with basic searches and do not be too complicated. DO NOT USE TOO MANY TERMS AT ONCE
Be sure to use period-specific language.
Do NOT search a bunch of terms. This will give more, not less, false its.