Periodicals, i.e., journals and magazines are typically categorized into three types:
Academic/Peer-Reviewed/Research-based/Scholarly
The journals in this category are written by experts, researchers, and scholars. They are published by professional organizations or educational institutions. The articles are text-based with few to no visual, except for graphics to visually organize the data. The articles go through a strict review process prior to being published. Research-based articles/Research reports are most often published in this type of journal.
Professional/Trade
The journals/magazines in this category are written by professionals in a given profession or trade. The articles may or may not be reviewed, and are published by professional associations or publishers known to publish subject-specific content. The publications typically have graphics, job opening announcements, and product advertisements relative to the profession or trade.
Popular
The magazines in this category may be written by freelance writers. The publications are glossy and attention-grabbing, and are filled with graphics and advertisements. The publications focus on a variety of interests based according to gender, entertainment, hobbies, news, and other special interests. Examples of this type include: Bride; Fortune; Men's Fitness; Sunset
Primary sources provide an account of an event or person as close to the occurrence as possible. Primary sources often include:
Addresses, speeches, interviews
Art work
Audio or Video recordings (radio or television program)
Autobiographies
Correspondence, letters (e-mail)
Data sets
Documentaries (may also be Tertiary)
Historical fiction
Minutes of meetings
Newspaper articles
Original legal documents (birth certificates, wills, etc.)
Research-based articles/Research reports
Secondary sources are those which provide application, commentary, evaluation, or interpretation of a primary source. Keep in mind that different disciplines may define primary, secondary, and tertiary sources differently. In most cases, secondary sources include:
Biographies
Bibliographies (may also be Tertiary)
Commentaries/Criticisms
Encyclopedias (may also be Tertiary)
Journal and magazine articles
Non-fiction monographs (books)
Tertiary sources are information sources which present a combination of both primary and secondary type information. In most cases, tertiary sources include:
Bibliographies (may also be secondary)
Subject-specific dictionaries and encyclopedias (may also be primary or secondary)
Journal/magazine articles (may also be primary or secondary)
Textbooks (may also be secondary)