There are a number of different definitions for primary literature. These can vary according to the academic discipline (ie. science or humanities). In brief:

These are original materials which have not been filtered through interpretation, condensation, or, often, even evaluation by a second party; for example journal articles, monographs, reports, patents, theses, diaries, letters, photographs, poems.


Some definitions of primary sources

Primary sources are original materials on which other research is based.

They are usually the first formal appearance of results in the print or electronic literature (for example, the first publication of the results of scientific investigations is a primary source).

They present information in its original form, neither interpreted nor condensed nor evaluated by other writers.

They are from the time period (for example, something written close to when what it is recording happened is likely to be a primary source).

Primary sources present original thinking, report on discoveries, or share new information.


Examples of Primary Sources

Scientific journal articles reporting experimental research results. 

Proceedings of Meetings, Conferences and Symposia. 

Technical reports. 

Dissertations or theses (may also be secondary). 


Sets of data, such as census statistics. 

Works of literature (such as poems and fiction). 



Interviews, surveys and fieldwork. 

Letters and correspondence. 


Newspaper articles (may also be secondary). 

Government documents. 

Photographs and works of art. 

Original documents (such as birth certificate or trial transcripts). 

Internet communications on email, listservs, and newsgroups.


What are Primary Sources?

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. Often these sources are created at the time when the events or conditions are occurring, but primary sources can also include autobiographies, memoirs, and oral histories recorded later. Primary sources are characterized by their content, regardless of whether they are available in original format, in microfilm/microfiche, in digital format, or in published format. Primary sources can be found in nearly all of Yale's twenty-two libraries as well as at the Peabody Museum of Natural History, the Yale Center for British Art, and the Yale Art Gallery. See the “Tools for Discovery” page for tips on identifying materials relevant to your research. 


Printed or Published Texts


Books & Pamphlets

Determining what is a primary source can be tricky, and in no case is this more apparent than with books and pamphlets. From one vantage point, books are the quintessential secondary source: scholars use primary source materials such as letters and diaries to write books, which are in turn secondary sources. However, books can also be a rich source of primary source material. In some instances, as in the case of published memoirs, autobiographies, and published documents, it is easy to determine when a book functions as a primary source.

But even secondary source materials can function as primary sources. Take, for instance, Lytton Strachey’s famous history of nineteenth century England, Eminent Victorians, first published in 1918. On one hand, Eminent Victorians is a secondary source, a history of English society and culture in the 1800s based on Strachey's research and analysis of primary sources. On the other hand, a present-day scholar could treat Eminent Victorians itself as a primary source, using it to to analyze the mores and attitudes of Lytton Strachey and the early twentieth century English intelligentsia of which he was a part.


Serials (newspapers, periodicals, magazines)

A serial is a publication, such as a magazine, newspaper, or scholarly journal, that is published in ongoing installments. Like books, serials can function both as primary sources and secondary sources depending on how one approaches them. Age is an important factor in determining whether a serial publication is primarily a primary or a secondary source. For instance, an article on slavery in a recent issue of the Journal of Southern History should be read as a secondary source, as a scholar’s attempt to interpret primary source materials such as ledgers, diaries, or government documents in order to write an account of the past. An article on slavery published in the Journal of Southern History in 1935, however, can be read not only as a secondary source on slavery but also and perhaps more appropriately, it can be read as a primary source that reveals how scholars in the 1930s interpreted slavery.


Government Documents

A government’s documents are direct evidence of its activities, functions, and policies. For any research that relates to the workings of government, government documents are indispensable primary sources.

A wide range of primary sources are found in government documents: the hearings and debates of legislative bodies; the official text of laws, regulations and treaties; records of government expenditures and finances; statistical compilations such as census data; investigative reports; scientific data; and many other sources that touch virtually all aspects of society and human endeavor. This information comes in a similarly wide variety of formats, including books, periodicals, maps, CD-ROMs, microfiche, and online databases.

What makes all these sources “government documents”? What all these sources have in common is that they are published or otherwise made available to the general public by a government for the general public, at government expense or as required by law. They are a government's official “voice.” Government documents are usually housed in separate sections of libraries, and have their own specialized arrangement and finding aids.

Note that government document collections typically do not include primary legal sources such as court decisions and law codes, which are often published by for-profit publishers and are found either in the main library collection or in separate law libraries.

For decades the U.S. government has been the largest publisher in the world, but government documents are also produced by regional, state, and local governments, and by international bodies such as the United Nations and the European Union.

Many government documents published before the late twentieth century are not listed in online catalogs or databases; for more information, contact the Government Documents and Information Center, Yale University Library, or Research Resources, Yale Law Library.


Manuscript and archival material

Manuscript and archival materials are unique resources that can be found in only one library or institution (though digital copies or copies on microfilm or microfiche may be available elsewhere). They are valuable primary source material for researchers in many fields of study, including history, political science, sociology, literature, journalism, cultural anthropology, health sciences, law, and education. Manuscripts and archival materials are distinct from other library materials in the ways they are described, accessed, handled and evaluated.


Manuscripts and archives are unpublished primary sources. The term archives, when it refers to documents, as opposed to a place where documents are held, refers to the records made or received and maintained by an institution or organization in pursuance of its legal obligations or in the transaction of its business. The term manuscripts, which originally referred to handwritten items, refers now to a body of papers of an individual or a family. Both terms can encompasses a broad array of documents and records of numerous formats and types. Archival records or manuscripts may include business and personal correspondence, diaries and journals, legal and financial documents, photographs, maps, architectural drawings, objects, oral histories, computer tape, video and audio cassettes. See also: Visual Materials and Realia/Artifacts.



Maps are primary sources because they are created in particular cultural contexts. Mapmakers may have hidden agendas or be influenced by political or social factors. Maps may reveal misperceptions or deliberate misrepresentations.


Realia / Artifacts

Once functional objects used by people, realia and artifacts convey important information about the lives and histories of peoples. Realia and artifacts are three-dimensional and unlike two-dimensional objects such as books and manuscripts, can be either man-made or naturally occurring. While all collected realia and artifacts are deemed as having documentary value, some are valued for their intrinsic worth, others for their artistic merit, and others for their historical significance or scientific value. Realia and artifacts commonly used for research are: War memorabilia such as canteens, mess kits, and uniforms Emblems and badges

. Cards and board games

. Jewelry, clothing, and textiles

. Leather goods

. Needlework

. Hair, wool, and silk


Visual Materials

The term “visual material” refers to any primary source in which images, instead of or in conjunction with words and/or sounds, are used to convey meaning. Some common and useful types of visual materials are as follows:

. Original art, including but not limited to paintings, drawings, sculpture, architectural drawings and plans, and monoprints.

. Prints, which are works produced in multiple but limited numbers such as woodcuts, engravings, etchings, and lithographs

. Graphic arts, including materials such as posters, trade cards, and computer generated graphics

. Photographs

. Film and video

Any of these materials can provide valuable information to a researcher. Factual information can often be extracted from visual materials; however, the best information imparted by these materials is often of a subjective nature, providing insight into how people see themselves and the world in which they exist.


Oral History

Oral history interviews and video memoirs provide important perspectives for historians. Since the invention of the tape recorder in the 1950s, oral history projects of many kinds have proliferated, ranging from the “man-on-the-street” type of interview to the more formal Presidential archives. Oral history projects usually are centered on a theme, such as Yale’s Oral History American Music project, which is dedicated to the collection and preservation of oral and video memoirs in the voices of American musicians.



Dissertations are book-length studies based on original research and written in partial fulfillment of requirements for the doctoral degree. Although usually secondary sources, dissertations can themselves be primary sources or can be extremely helpful in identifying and locating primary sources.


Dissertations that can be primary sources might be edited versions of texts or could be used to analyze the influence of a professor on a generation of graduate students and, by extension, on the teaching and writing in a discipline over a period of time. Because a dissertation is based on original research, its bibliography will contain references to primary sources used by the author and can often lead to manuscripts, diaries, newspapers and other primary material of interest.




As reproduction of historical newspaper articles and/or historical sources and/or historical artifacts, these pages may contain translation errors and/or spelling and/or missing words and/or missing pages and/or poor pictures, etc.