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Types of Sources: Defining Sources

A guide that provides information on types of sources and how to find them.

Types of Sources

Your topic and research question or thesis statement will determine which resources are best. If you are struggling to find information in scholarly sources, but can find information on the open web, that is a sign you need to re-evaluate your topic or research question. See the "What Sources Should I Use" for more help with this issue.

A primary source is the original source of information on a topic. The source is usually created at the time of study. What defines a primary resource varies slightly with each discipline. Typically, artifacts, diaries and manuscripts, autobiographies or memoirs, photographs, audio files of interviews before editing, blogs and vlogs published and produced by the creator at the time of an event are considered to be primary information sources. See the page about primary sources in this guide for more information about primary sources.

Some information sources may be available in audio or video. Most books and articles are available either in print or online. Books may be available in paperback, hardback, large print or other types of editions or formats. The format and edition of an information source may affect whether the item is considered to be a primary source (the original source of information or an exact replica) or not.  However it is usually difficult to tell when something is an exact replica of the original.

Sources can be defined as primary, secondary, and tertiary levels away from an event or original idea. Researchers may want to start with tertiary or secondary source for background information. Learning more about a topic will help most researchers make better use of primary sources.

Group of Taft College representatives receiving a check while standing outside of the Taft College Library. Photograph documenting the renaming of the Taft College Library is an example of a primary source.

Taft College naming of the library December 14, 2017

Information Timeline


Time After Event


Sources for Information


Tools for locating the Information

Seconds/Minutes                                                                                              Radio, TV, Internet                           Websites and Web Search Tools
Day to Days


(both print and electronic)

Newspaper Indexes (such as ProQuest)
Week  to  Weeks

Popular Magazines

(both print and electronic)

Periodical Indexes

(EBSCOhost, ProQuest, etc.)

Weekly to 1 or more Years                      

Reference Sources:

  • Statistical and Hot Topics
Reference Tools such as CQ Researcher, Statistical Abstracts. Reference Databases. Specialized websites.
6 Months or more

Scholarly and Academic Journals

(both print and e-Books)

Periodical Indexes (EBSCOhost, ProQuest, etc.) Subject Bibliographies.

2 Years or more

Books and e-Books

Library Book Catalog, bibliographies, work cited lists. Web tools such as Google Books and WorldCat.
Average of 10 Years

Reference Sources:

  • Subject Encyclopedias, Handbooks, etc. (both print and electronic)
Library Book Catalog, bibliographies, work cited lists. Web tools such as Google Books and WorldCat.

Adapted from Sharon Hogan's "Flow of Information" conceptual approach to library instruction and UCLA College Library.

How to evaluate both print and web information. C: currency and credibility; is the information current? when was the site created? when was it updated? are links on this site still active? what organization is responsible for publishing it? R: Relevence and reliabilty; is the information provided appropriate for your research topic? does the site provide good coverage on your topic? is there a bibliography or list of references? do you feel comfortable citing this page in a college-level assignment? A: Authority and Audience; can the author of the site be identified? who is responsible for the content of the material- a person or organization? is contact information given for the author and/or site? what are the author's qualifications- education, occupation, years of experience, and expertise? is the author affiliated with an institution or organization? P: purpose and point of view; can  you find an about us page? does it state a purpose or mission? is the site scholarly or popular? are there ads on the site? what type of site is it? .com= commercial, .gov= government, .edu= educational, .net= network, .mil= military, .org= non-profit organization

Finding Authoritative Information

Academic encyclopedias, Authority for academic encyclopedias: look for Authors that are scholars and that they are Edited by professionals. Academic encyclopedias are Useful for: Background, overviews, and getting started. Find academic encyclopedias: In Print such as a Reference Collection in the library, and or Online – in the Library Databases. Books and e-books.  Authority for books and e-books: you should look for author’s credentials, look for publisher’s credentials. Books and e-books are Useful for: In-depth information, historical perspective, and leads to other sources.   Websites.  Authority for websites, look for authors that are verified, sites may or may not be edited.  Websites are useful for: background, overviews, getting started, and links to other sources.  Find websites: in search engines, subject directories, and recommendations.  Academic Journals.  Authority for academic journals, look for authors that are scholars and are edited by professionals. Academic journals are useful for: In-depth research, and primary research.  Find academic Journals: Online in library databases or in google scholar.  Popular Magazines. Authority for popular magazines look author’s credentials, that they are edited by professionals, and or possibly influenced by ads.  Popular magazines are useful for: current events and popular opinion.  Find Popular magazines: online in library databases, and newsstands.  People.  Authority for people: they must be verified.  People are useful for contemporary views, personal expert opinions, and primary accounts.  Find People: by recommendations, online organizations, online social networks, yellow pages, and blogs.

What Sources Should I use?  Questions suggested by the topic: violence and the media, and child violence.  Types of sources you could use to answer those questions. Question 1. Where can I find background information on violence and media, and child violence?  Answer: Look for subject encyclopedias, such as the Encyclopedia of psychology. Question 2. What research has already been done?  Answer: Look for books form scholarly and academic publishers.  Question 3. What kinds of methods have scholars used to study this question, what are the results? Answer: look for research articles in scholarly, academic journals; look for books from academic publishers.  Question 4. How does the popular press treat stories of violent acts by children? Answer: look for popular magazine articles, newspapers.  Question 5. What are some specific examples of acts of violence by children? Answer: look for popular magazine articles, newspapers. Question 6. Are there any first-person accounts of violence by children?  Answer: look for primary source material: letters to the editor, blog postings, and interviews published in reputable journals and books.  Question 7. What are the views of professionals such as psychiatrists and doctors? Answer Look for official websites for psychological and medical organizations.  Question 8. Where can I find statistics on whether violent acts increase with the number of tv watched? Answer: Look through reference books, statistical websites, scholarly journals, books.

Types of Periodicals

Periodicals are available in numerous formats, and are published for a variety of audiences. They offer news accounts, opinion, commentary, perspective, scholarly analysis, and reports of research findings. Periodicals are published at regular intervals - daily, weekly, monthly, quarterly, etc. The main categories of periodicals are described below. NOTE: Some professors may require that you use only periodicals that fall within the Scholarly/Research Journal category. Check with your professors to clarify their expectations before you begin your research. 



Characteristics Indexing


New York Times 

Bakersfield Californian  

USA Today

  • Current information
  • News stories
  • Opinion and commentary
  • Advertisements, classifieds
  • Geographic focus

Newspaper Indexes:

New York Times Index

Custom Newspapers

LexisNexis Academic

World Wide Web

Trade Journals:


Aviation Week & Space Technology

Chain Store Age

  • Written for practitioners in applied fields
  • Product information
  • Current trends and practices
  • Advertisements

Business and General Indexes:

Business and Company Resource Center

Business Full Text

Popular Magazines:




Business Week

Sports Illustrated

  • Written for general public
  • Current event overviews
  • many color illustrations
  • Non-technical language
  • Many advertisements
  • For entertainment

Magazine Indexes:

Readers' Guide Full Text

Expanded Academic ASAP

Research Library

Journals of Opinion:

New Republic


American Spectator

National Review

  • Written from particular viewpoint (political, religious, activist, etc.)
  • For general educated audience
  • Commentary on politics, society
  • Book reviews

General Indexes:

Reader's Guide Full Text

Expanded Academic ASAP

PAIS (Public Affairs Information Service)

Scholarly/Research Journals:

Journal of Marriage and The Family

New England Journal of Medicine

American Art Journal

Modern Fiction Studies

  • Written for professionals
  • Reports of original research
  • In-depth analysis
  • Few advertisements
  • Charts and graphs
  • Technical vocabulary
  • Usually contain: Abstract, Introduction, Methodology, Results, Conclusion, and Bibliography

Specialized Indexes:

Social Sciences Full Text

BIOSIS Previews (biology

Criminal Justice Abstracts

MEDLINE (medicine)

ABI/INFORM (business)

Art Full Text

PsycINFO (psychology)


How to Distinguish Between Types of Periodicals infographic