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Waidner-Spahr Library

Citing Sources: GSA

Specific Information about In-Text citations

With the GSA Style, quotations and borrowed phrases are indicated as such within the text, with the author's name and page number cited in parentheses. This variation is used instead of footnotes or endnotes.

When quoting or paraphrasing an author, begin the sentence by including the author's name followed by the date of publication in parentheses. At the end of the quote or paraphrase, include the page number(s) in parentheses. See example below.

According to Smith (2008), "warmer ocean temperatures can lead to the development of stronger hurricanes" (p. 133).

If the name of the author is not included within the sentence, include the author's name and the publication year at the end of the sentence with the relevant page number(s). For example:

"Warmer ocean temperatures can lead to the development of stronger hurricanes" (Smith, 2008, p. 133).


Multiple Authors:

To cite a publication with two author, include both authors' last names either within the sentence or in parentheses at the end of the sentence.

For publications with 3-5 authors, include the last name of each author the first time the publications is cited. For subsequent citations include only the last name of the first author and the phrase et al.

For publications with 6 or more authors, list the name of the first author followed by the phrase et al. for all citations.

Sample Citations

(All of the following samples are taken from the Geological Society of America online style guide)

Book with a Single Author:

(Note that first and middle initials are used for authors, only the first word of the title is capitalized, and that commas are used extensively)

Weaver, C.E., 1989, Clays, muds and shales: Amsterdam, Elsevier, Developments in Sedimentology, v. 44,

819 p.

Book with Two Authors:

Twiss, R.J., and Moores, E.M., 1992, Structural geology: New York, W. H. Freeman and Company, 532 p.

Scholarly Article:

Leigh, D.S., 1994, Roxana silt of the Upper Mississippi Valley: Lithology, source, and paleoenvironment:

Geological Society of America Bulletin, v. 106, p. 430–442.


(Note that scale, series number and number of sheets all need to be included if available)

Abrams, G.A., 1993, Complete Bouguer gravity anomaly map of the State of Colorado: U.S. Geological Survey

Miscellaneous Field Studies Map MF-2236, scale 1:500 000, 1 sheet.

Ernst, W.G., 1993, Geology of the Pacheco Pass quadrangle, central California Coast Ranges: Geological Society

of America Map and Chart Series MCH078, scale 1:24 000, 1 sheet, 12 p. text.

Proceedings from a conference or symposium:

Baar, C., 1972, Creep measured in deep potash mines vs. theoretical predictions, in Proceedings, Canadian Rock

Mechanics Symposium, 7th, Edmonton: Ottawa, Canada Department of Energy, Mines and Resources, p. 23–77.


Advanced National Seismic System, 2007, ANSS global earthquake catalog:
 (accessed November 2007).

Scotese, C.R., 2003, PALEOMAP Project: (accessed August 2011).

For more examples, look at a recent issue of Geology or the Geological Society of America Bulletin in order to see how the authors formatted their citations.


Citing Resources in GSA Style

General Information about Citing in GSA Style

The Geological Society of America is the citation style used by the Earth Sciences department at Dickinson.

While the citation style guidelines of the GSA are not as detailed as those of many of the other citations guides it does have some specific details that are worth noting. The full details of its requirements are available at the online GSA Reference Guidelines (PDF).

Specific Information about Bibliographies

  • The bibliography is arranged in alphabetical order by authors’ last names.
  • The author always comes first with last name followed by first name, separated with a comma. Names of subsequent authors are written naturally. For four or more authors, the abbreviation “et al.” (“and others”) is used after the name of the first author.
  • Second and all subsequent lines are always indented.
  • Authors' first and middle names are never spelled out in the GSA style. Initials are always used for first and middle names.


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Zotero is a free, open source Bibliographic Management Tool recommended by Dickinson librarians. Please visit the Zotero Guide for more information about what Zotero is and how to use it.