Definition: Original documents created or experienced contemporaneously with the event being researched. These can vary slightly depending on which academic discipline you are researching in.
Characteristics: In the Humanities, look for first-hand observations, contemporary accounts of the event, viewpoints of the time. In the Natural & Social Sciences, look for empirical studies, such as reporting the results of an experiment, or a case study.
Definition: Works that analyze, assess, or interpret an historical event, era, phenomenon, or similar group of experiments, generally utilizing primary sources to do so.
Characteristics: Interpretation of information, usually written well after the event, and offers reviews, critiques, or analyses.