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Primary, Secondary and Tertiary Sources

SIA New York Library Guide

Primary Sources

Public Domain Mark
This work (Constitution of the United States, page 1), identified by National Archives and Records Administration, is free of known copyright restrictions.


This guide will introduce students to three types of resources or sources of information: primary, secondary, and tertiary.

Definition of a Primary Source: 

Primary sources are firsthand documents that provide direct evidence on your topic.  

The Library of Congress refers to them as the "raw materials of history — original documents and objects which were created at the time under study. They are different from secondary sources, accounts or interpretations of events created by someone without firsthand experience."

A primary source is most often created during the time the events you are studying occurred, such as newspaper articles from the period, correspondence, diplomatic records, original research reports and notes, diaries etc. They may also include items created after the events occurred, but that recount them such as autobiographies and oral histories.

Types of Primary Sources
Original Documents Creative Works Relics and Artifacts
Diaries Art works Pottery
Speeches Novels Decorative arts
Correspondence Poetry Clothing
Interviews Music Buildings
Manuscripts Architectural drawings/plans Textiles
Government Documents Photographs Needlework
News film footage Film  
Archival Materials    

Secondary Sources

Definition of a Secondary Source: 

Secondary Sources are accounts written after the fact with the benefit of hindsight. They are interpretations and evaluations of primary sources. Secondary sources are not evidence, but rather commentary on and discussion of evidence.¹

¹‚Äč Yale University Library, "Primary, secondary & tertiary sources"

Types of Secondary Sources
Secondary Sources
Biographical works
Commentaries, criticisms
Conference proceedings
Essays or reviews
Literary criticism such as journal articles
Magazine and newspaper articles
Monographs, other than fiction and autobiographies
Reprints of art works
Textbooks (could also be considered tertiary)
Websites (could also be considered primary)

Tertiary Sources

Definition of a Tertiary Source

A tertiary source presents summaries or condensed versions of materials, usually with references back to the primary and/or secondary sources. 

Types of Tertiary Sources
Tertiary Sources

Primary and Secondary Sources in Law

Primary Source in Law: 

A statement of the law itself from a governmental entity, such as a court, legislature, executive agency, President or Governor.

Secondary Source in Law: 

Materials that discuss, explain, interpret, and analyze what the law is or what it should be.


Examples of Primary and Secondary Sources in law
Primary Sources in law Secondary Sources in law
Code of Federal Regulations Articles about law
Contracts, wills, other legal documents Books about law
Court decisions Law reference books
Federal Registrar  Law reveiws
US Code Legal news
Text of legislative bills  

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