Citing Your Sources

Citation styles vary from discipline to discipline. If you're not sure what style you should use, ask your instructor. If you are in a lower level course and your instructor wants you to cite your sources but does not express a preference, you may decide to choose one that's common in the field in which you plan to study.

Commonly used styles include:

  • APA (American Psychological Association)
  • MLA (Modern Language Association)
  • Chicago Manual of Style (or CMOS)
  • Turabian


APA, the style of the American Psychological Association, is used in the social sciences, primarily in

  • psychology
  • sociology
  • business
  • nursing
  • social work
  • criminology
  • education.

APA requires citations to appear in two places:

  1. brief parenthetical citation containing the author's last name and publication year placed in the text itself directing the reader to the full citation, and
  2. the full citation found in the References section and arranged alphabetically at the end of the text.

An in-text citation in which the writer does not mention the author's name in his or her text would look like this:

(Mellers, 2000).

With this information, your reader can then check the References and find the work the writer is referring to:


Mellers, B. A. (2000). Choice and the relative pleasure of consequences. Psychological Bulletin, 126, 910−924.

For the most up-to-date and authoritative answers to questions about APA, see:

Publication Manual of the American Psychological Association (6th ed.), published by the American Psychological Association in 2010.

Service desks in Evans Library, Library Annex, West Campus Library, Policy Sciences and Economics Library, and Medical Sciences Library each have a copy or copies of this book (BF76.7 P83 2010). In addition, copies can be checked out from the Evans Library and West Campus Library.

The library also provides an APA handout in a PDF-downloadable file for your convenience.

For additional help with electronic resources in APA style, see


MLA, the style of the Modern Language Association, is used in the humanities, primarily in

  • English
  • languages
  • speech
  • communication.

MLA requires citations to appear in two places:

  1. parenthetical reference placed in the text itself that directs the reader to the full citation
  2. Works Cited, an alphabetized list that contains full publication information for each source and is placed at the end of the text.

An in-text parenthetical citation in which the writer does not mention the author's name in his or her text would look like this: (Faigley 47).

If the author's name is used in the text of the paper, then there is no need to mention it again; just the page number serves as a reference: (47).

With this information, your reader can then check the Works Cited and find the work the writer is referring to:

Works Cited

Faigley, Lester. Fragments of Rationality: Postmodernity and the Subject of Composition. Pittsburgh: U of Pittsburgh P, 1992. Print.

For the most up-to-date and authoritative answers to questions about MLA see the MLA Handbook for Writers of Research Papers (7th ed.), by Joseph Gibaldi and Phyllis Franklin, published in 2009.

Evans Library has several copies of this book (LB2369.G53 2009) that you can check out, and the Humanities reference desk also has copies for your use in the library.

The library also provides an MLA Documentation handout that can be printed off the web.

Chicago Manual of Style

The Chicago Manual of Style has its origins at the University of Chicago where it can be traced back to a single style sheet in the 1890s, although the first edition of the manual was not published until 1906. It offers two systems of documentation:

  1. a note-bibliography style used predominantly in history and some humanities, and
  2. an author-date system used primarily in the sciences.

The note-bibliography system places a superscript number in the text, which points to a note, either a footnote at the bottom of the page or an endnote at the end of the paper or chapter. An alphabetically arranged bibliography at the end of the text or book provides a complete list of all sources used in the work. The paper excerpt that follows demonstrates the in-text number, which points to a note referencing a journal article. The note could be either an endnote or a footnote. A bibliography entry for the same text follows:

Reflection-in-action is the process of revising and reviewing that takes place while writing; this process was first described by Sharon Pianko in her groundbreaking article, "Reflection: A Critical Component of the Composing Process." According to Pianko, "The ability to reflect on what is being written seems to be the essence of the difference of able and not so able writers."1

1. Sharon Pianko, "Reflection: A Critical Component of the Composing Process," College Composition and Communication 30 (1979): 276-278.


Pianko, Sharon. "Reflection: A Critical Component of the Composing Process." College Composition and Communication 30 (1979): 276-278.

Notice that in the note, the author's name is given first name first because there is no need for alphabetizing. Notes appear at the bottom of the page (footnote), or in a list arranged in numerical order at the end of the text (endnote). However, since the bibliography is arranged alphabetically, the author's name is given last name first.

In the author-date system, the author's last name and the date of publication are provided in a parenthetical reference within the text. The parenthetical citation directs the reader to a list of references at the end of the text or chapter. The following excerpt from R.M.M. Crawford's 2003 article provides an example of Chicago's in-text documentation. The entry that would appear in the Reference list for this selection follows:

Depriving a plant of oxygen at any time of the year is dangerous, but plants are more likely to survive the severe conditions of flooding and the "oxygen deprivation" that can result in summer months than in winter (Crawford 2003).


Crawford, R.M.M. 2003. Seasonal differences in plant responses to flooding anoxia. Can J Bot 81: 1224-1246.

***Notice the abbreviated journal title in the reference example; Can J Bot stands for Canadian Journal of Botany. In many branches of science, standard abbreviations for journals are required. Reference works such as BIOSIS and Index Medicus can supply these, but you can also ask at the library's reference desks.

The Chicago Manual of Style (Z253 .U69 2010), now in its 16th edition, is available near the main service desk in the Evans Library. You can also access a library handout Libraries' website.

When you are looking at different sources of information for this style, please remember to be mindful of the two different systems!


The Turabian style is named for Kate Turabian, University of Chicago's dissertation secretary from 1930 to 1958 who apparently developed what she considered a more user friendly version of the Chicago style for students. Over time, it has developed into a separate style; and, while there are some differences, the two are still very similar.

Like the Chicago style, Turabian uses two methods of documentation:

  1. The better known method is a note-bibliography system long used in history and the humanities.
  2. Turabian also includes a parenthetical author-date system more appropriate to the natural and social sciences.

In the note-bibliography documentation style, a number or symbol in the text refers to a note at the foot of the page or at the end of the text. These footnotes (or endnotes), in turn, are keyed to entries in a separate list (a bibliography), which appears at the end of the text and which includes all the sources used to write the paper. Bibliographies are usually arranged alphabetically; however, in some cases they may be arranged chronologically or by type of resource.

The basic note-bibliography system is illustrated in the following example:

Although Charles Dickens is most closely associated with London, he felt a great affinity for Paris, as well. Peter Ackroyd writes eloquently of the appeal that Parisian light and clarity held for the novelist's need for brightness and order.1 A later critic, Grahame Smith, has examined the relative positions that the two cities occupied in Dicken's fictional universe, noting that the novelist depicted the British capital as a shadowy labyrinth and its French counterpart, by contrast, as a sparkling, kaleidoscopic panorama.2

1Peter Ackroyd, Dickens (New York: HarperCollins Publishers, 1990), 443-4.

2Grahame Smith. "Dickens and the City of Light." Dickens Quarterly 16, no. 3 (September 1999): 178-190.


Ackroyd, Peter. Dickens. New York: HarperCollins Publishers, 1990.

Smith, Grahame. "Dickens and the City of Light." Dickens Quarterly 16, no. 3 (September 1999): 178-190.

In Turabian's author-date documentation system, the name of a source's author and the date of its publication appear in parentheses in the text. If a specific page is referred to, the page number may also be included in the parenthetical reference. Full publication information for the source is provided in an entry in a separate reference list which may be titled References, Works Cited or Literature Cited. Like bibliographies, reference lists are arranged alphabetically by author.

The basic Author-Date method is illustrated in the following example:

In the last decade, problems paying attention have joined obesity and aggression as ills attributed to excessive television viewing in childhood. One researcher posits the following connection: "Fast-paced, nonlinguistic, and visually distracting television may literally have changed children's minds, making sustained attention to verbal input, such as reading or listening, far less appealing than faster-paced visual stimuli." (Healy, 1998, 32) This assertion was given powerful support recently by a longitudinal study which included 1,278 one-year-olds. This study found that that, for every 2.91 hours of television watched daily at age one, there was a 28 percent increased risk of developing attentional problems by age seven. (Christakis, et al. 2004, 710)

Works Cited

Christakis, Dimitri A., Frederick J. Zimmerman, David L. DiGiuseppe, and Carolyn A. McCarty. 2004. Early Television Exposure and Subsequent Attentional Problems in Children. Pediatrics 113: 708-713.

Healy, Jane M. 1998. Failure to Connect: How Computers Affect Our Children's Minds—for Better and Worse. New York: Simon & Schuster.

In the example above, the first parenthetical citation and its corresponding entry in the Works Cited list refer to a book by a single author. The second citation-reference list pair refers to an article by more than three authors.

More examples of Turabian Author-Date style can be found in a library handout.

For a more in-depth treatment of both documentation methods, including examples, a copy of Turabian's A Manual for Writers of Research Papers, Theses, and Dissertations (7th ed.) is available at the Policy Sciences and Economics Library reference desk.


CSE, the style recommended by the Council of Science Editors, was developed initially for the life sciences and biomedicine, but has expanded to includemathematics and the natural sciences.

In the CSE style, a "citation" in the text points to a "reference" listed at the end of the document. Two forms of citation are permitted in CSE style:

1. the citation-sequence (C-S) system and

2. the name-year (N-Y) system.

In the citation-sequence system, citations in the text are numbered consecutively in the order they are cited. These numbers correspond to the references, which are listed at the end of the document in the order they were cited in the text. For example:

In-text citation: Bacterial communities in the ocean may secrete substances that inhibit the growth of other species (1).

Reference: (1) Long RA, Azam F. Antagonistic interactions among marine pelagic bacteria. Applied and Environmental Microbiology 2001 (67):4975-4983.

In the name-year system, citations in the text consist of the author's surname and the publication year. Complete references are listed alphabetically at the end of the document. For example:

In-text citation: Bacterial communities in the ocean may secrete substances that inhibit the growth of other species (Long and Azam 2001).

Reference: Long RA, Azam F. 2001. Antagonistic interactions among marine pelagic bacteria. Applied and Environmental Microbiology 67:4975-4983.

For more examples and in-depth treatment, copies of Scientific style and format : the CSE manual for authors, editors, and publishers (7th ed.) are available at in the Evans Library (T11 .S386 2006)

More examples are available in a handout provided by the TAMU Libraries.

Electronic Citations

The emergence of the Internet and the explosion of online publishing have given rise to a whole new class of source material, making the access of information easier for students and scholars than at any other time in history. However, easy access is not without its costs! For example, how do we cite all these new sources?

Web pages don't exactly fit into the same citation format as the pages of a book, journal, or magazine. Electronic materials can appear in online databases, on CD-ROM format, as email or listserv messages, and in a variety of other forms. Each of these forms must be acknowledged by name in your citations.

You will also find there are many variations among the accepted citation styles on how to cite electronic resources. Because different disciplines rely on different style guidelines, it isn't possible to provide you with just a few examples of documentation types that will illustrate all cases. In fact, even journals in the same field often vary in their interpretations of how a particular source should be cited, whether in print or electronically.

So what should you do then? First, check with your instructor to see if he or she has any specific guidelines for electronic resources or a preferred citation style or journal format for his or her discipline. Then, check out the library's resources. This handout includes web addresses for the major citation styles covered in this tutorial. These websites will be the best source for the latest updates on citing electronic material.

Recommended Resources

St. John's University, Information Literacy Tutorial

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