Principles of Source Citation (National Institute)

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The original content for this article was contributed by The National Institute for Genealogical Studies in June 2013. It is an excerpt from their course Research: African American Ancestors  by Michael Hait, CG. The Institute offers over 200 comprehensive genealogy courses for a fee ($).

Principles of Source Citation

The importance of proper source citation cannot be emphasized enough. By properly recording the sources of your evidence—the documents used, the creator of the documents, and the location of the documents, among other important details—you can not only revisit information later, but you will also gain insight into the quality of the evidence you are using. Moreover, if someone else were to look at your research, they will also be able to locate and understand the source that you used, and evaluate it on their own. This ability will help to provide confirmation of the accuracy of your research, as well as help someone else working on a different, but related, problem.

There are several elements common to every source citation, regardless of the type and form of the record:

  • Creator
  • Title (or description of unpublished/untitled material)
  • Type of Source (e.g., birth certificate)
  • Date of the Record
  • Location
  • Format (e.g., microfilm, digital image)
  • Repository (e.g., the current location of the source)

The two books by Elizabeth Shown Mills, Evidence! and Evidence Explained, are highly recommended. They not only delve into the details of evidence analysis, but also provide guidelines for citing nearly every source imaginable, based on the Chicago Manual of Style as adapted by the author to address citation of original records.

The following examples show how to cite some common record groups in your reference notes (such as footnotes or endnotes). These guidelines can be altered to meet your specific needs or to conform to in-house citation rules for various repositories. However, you should include at least as much information as is provided in these examples—never less.

  • 1870 U.S. Census, Halifax County, North Carolina, population schedule, Littleton Township, Littleton post office, pg. 67 (written), pg. 455 (stamped), dwelling 565, family 565, Kemp Bowers; digital image, accessed 4 Aug 2008); from National Archives and Records Administration microfilm M593, FHL Film roll 1141.
  • William H. Green (—, Co. F., 6th Va. Colored Inf., Civil War), pension application no. 1,333,424, certificate no. 1,233,379, Case Files of Approved Pension Applications ..., 1861-1934; Civil War and Later Pension Files; Department of Veterans Affairs, Record Group 15; National Archives and Records Administration, Washington, D.C.
  • Maryland Department of Health, Bureau of Vital Statistics, death certificate no. 8464, George Barton Jr., 22 May 1917, PG, MSA SM30-38, microfilm no. SR 3050; Maryland State Archives, Annapolis.

Sources, Information, and Evidence

After you have found relevant records, you must evaluate the evidence. Part of this process involves determining the type of source, the type of information, and the type of evidence that you have collected.

Original Source

An original source, according to The BCG Genealogical Standards Manual, is “the person or record whose information did not come from data already spoken or written.” Wherever possible, original sources should be used. Most often, the original will be more readily available as an “image copy,” that is, microfilm, digital images, or photocopy. Assuming a high-quality image, an image copy can generally be treated the same as the original so long as you accurately cite the image copy itself.

Derivative Source

A derivative source is “a person or record that supplies information that is repeated, reproduced, transcribed, abstracted, or summarized from something already spoken or written.” Into this category fall published or unpublished transcripts, abstracts, or extracts. These should be used only sparingly, and are best used to point your research to the original source. However, there is an exception when dealing with land records. Deeds remain in the possession of the landowner; the “official” record is a clerk’s transcription into the county record book. This record book is technically a derivative copy, but since the original is only rarely available for review, in this case, using and citing the derivative is acceptable. It is the best available copy in most cases.

Each record or document you locate, every interview you collect, constitutes an individual source. Within each record lies information.

Primary Information

Primary information is “data contributed by a knowledgeable eyewitness to or participant in the event that is the subject of the record or by an official whose duties included making a full, accurate record of it.”

Secondary Information

Secondary information is “data supplied by a person who recorded it after hearing of the event or its details from someone else.” To make this determination, you must identify the informant for the record—the person who provided the information.

Every record can contain either primary information or secondary information, but many records contain both. For instance, a death certificate not only generally provides information on the death itself, which would generally be considered primary information (depending on the informant), but also may contain the decedent’s age or date of birth, place of birth, and parents’ names. This information would all be secondary in most cases (again depending on the informant), as the source of the information on the certificate rarely witnessed the birth of the same individual. Therefore, a death certificate would be a highly reliable source for the death information (primary) but a less reliable source for the birth information (secondary).


The final distinction that needs to be made is between direct evidence and indirect evidence. In general terms, evidence relates the information held in a record, to the question for which you seek an answer. Direct evidence, again as defined by The BCG Genealogical Standards Manual, is “an evidence item that is adequate by itself to answer the question.” Indirect evidence is “an evidence item that is incomplete in itself and therefore inadequate to answer the question at hand.” For example, a death certificate or gravestone provides direct evidence of a person’s date of death. The absence of an ancestor in federal census records after a given date provides indirect evidence that the person may have died prior to that date. However, the other possible explanations for this absence—such as migration or a misspelled name—do not allow the indirect evidence to be sufficient to prove death.

Again, a record may contain both direct evidence and indirect evidence, and in fact one piece of information may be both, depending on the question. For example, a birth certificate contains three pieces of information: the date of birth, the father’s name, and the mother’s name. This record would provide direct evidence of the birth itself, however, it also provides indirect evidence that the parents were married prior to that date.

When dealing with evidence, be careful not to “rest on your laurels.” Simply locating a document that provides the date of birth does not preclude the requirement that you continue to collect records relating to this question. Different records may contain different dates. As a genealogist it is not only your objective to obtain a date, but to obtain an accurate date, and account for any discrepancies or contradictory information.


Information in this Wiki page is excerpted from the online course Research: African American Ancestors offered by The National Institute for Genealogical Studies. To learn more about this course or other courses available from the Institute, see our website. We can be contacted at

We welcome updates and additions to this Wiki page.