Periodical (aka Serial) - A publication which is distributed on a regular basis, such as a journal, magazine, newspaper, or newsletter.
Scholarly publication (aka Journal) - A periodical that contains articles written by experts in a particular field of study. The primary audience is field study experts and students. Articles typically convey sophisticated and advanced knowledge. A scholarly publication is often but not always peer-reviewed.
Peer-reviewed publication (aka Refereed publication) - A type of scholarly publication. Before an article is accepted for publication in this journal, it is reviewed by several experts in the field who suggest possible changes and who recommend to the journal editor whether or not to publish the article.
Newspaper - A periodical issued at frequent intervals (usually daily, semi-weekly, or weekly) and containing news, opinions, advertisements, and other information of current and often local interest.
Popular publication (aka Magazine) - A periodical that informs readers about issues of common interest to the general public with an informal tone and scope. The articles use simple, non-technical vocabulary. The quality and content among publications can vary significantly. (e.g. Time, National Geographic, Sports Illustrated , Mother Jones)
Professional publication (aka Trade publication) - A periodical that contains articles by people working in a particular field of study. Covers news in the field, brief reports on research, and opinions about trends and events.
Primary Sources - Primary sources are original source materials. They are from the time period involved, have not been filtered through interpretation, and vary in format or material. (e.g. newspaper art icles, diaries, movies , literary texts, photographs, artifacts )
Secondary Sources - Secondary sources are accounts written after the fact with the benefit of hindsight. They are interpretations and evaluations of primary sources.