Primary Sources provide first-hand testimony or direct evidence concerning a topic under investigation. They are created by witnesses or recorders who experienced the events or conditions being documented at the time or after the event. Primary sources include autobiographies, memoirs, oral histories. legislative documents, court cases, case studies, longitudnal and other studies.
Secondary Sources are commentary or analysis of Primary Sources. Examples include biographies, critical essays on primary works, commentary on about primary sources including interpretations, persuasive articles, surveys and reference resources.
Popular magazines and newspapers: Written for the general public. These publications are written for informaiton and/or entertainment purposes. They are normally for-profit, and include advertising. They are published frequently, daily for newspapers, and weekly or monthly or bi-monthly for magazines.
Scholarly journals: Written by scholars or academics for scholars and those working on academic research. Articles must be approved by an editorial board of peer reviewers. Because a great deal of time is involved in their writing and production, journals are published less frequesntly, usually quarterly or even annually.
Trade publications: These may be magazines or journals, and are written for professionals in a particular field. Some are research related, most are not.