How Old Can References Be For Research Paper

Contributors: Kristen Seas, Allen Brizee.
Summary:

This workshop provides an overview of APA (American Psychological Association) style and where to find help with different APA resources. It provides an annotated list of links to all of our APA materials and an APA overview. It is an excellent place to start to learn about APA format.

APA Style Workshop

Welcome to the OWL Workshop on APA Style! This workshop will introduce you to important aspects of using the American Psychological Association (APA) Style to write and format research papers. You should begin with the introductory material, which covers what APA Style is, why it is used, and who should apply it to their work. Then you are invited to work through the OWL's handouts on APA Formatting and Writing Style, as well as APA Citations and Reference Lists.

NOTE: This workshop should answer most of your basic questions about using APA Style. However, if you are writing a complex document such as a thesis or lengthy manuscript, or if you have detailed questions, you should consult The Publication Manual of the American Psychological Association (6th edition), which you can usually find at your local library or in many bookstores.

The APA also has a website that allows you to order the book online and read some of their frequently asked questions about APA style. Purdue's OWL also has a list of Additional Resources covering APA style that you can consult.

What is APA Style?

APA Style establishes standards of written communication concerning:

  • the organization of content
  • writing style
  • citing references
  • and how to prepare a manuscript for publication in certain disciplines.

Why Use APA?

Aside from simplifying the work of editors by having everyone use the same format for a given publication, using APA Style makes it easier for readers to understand a text by providing a familiar structure they can follow. Abiding by APA's standards as a writer will allow you to:

  • Provide readers with cues they can use to follow your ideas more efficiently and to locate information of interest to them
  • Allow readers to focus more on your ideas by not distracting them with unfamiliar formatting
  • Establish your credibility or ethos in the field by demonstrating an awareness of your audience and their needs as fellow researchers

Who Should Use APA?

APA Style describes rules for the preparation of manuscripts for writers and students in:

  • Social Sciences, such as Psychology, Linguistics, Sociology, Economics, and Criminology
  • Business
  • Nursing

Before you adopt this style for your paper, you should check to see what citation style your discipline uses in its journals and for student research. If APA Style is appropriate for your writing project, then use this workshop to learn more about APA and how to follow its rules correctly in your own work.

APA Formatting and Writing Style

You should start by becoming familiar with the general formatting requirements of APA Style, as well as the different standards for writing that are expected among APA writers. Because APA is different than other writing styles, you should pay attention to everything from general paper layout to word choice. The following pages will introduce you to some of these basic requirements of APA Style to get you started in the right direction.

General APA Format

  • Covers the basic page layout for a typical APA manuscript, including everything from margin widths to the use of headings and visuals
  • Includes a general list of the basic components of an APA paper: title page, abstract, and reference page
  • Also includes a PowerPoint slide presentation with detailed information about the APA citation style

Types of APA Papers

  • Describes the two most common types of APA papers: the literature review and the experimental report
  • Outlines what sections must be included in each type of paper, from introductions to a methods section

APA Stylistics: Basics

  • Describes three basic areas of stylistic concerns when writing in an APA field: point of view, clarity/conciseness, and word choice
  • Explains how poetic language and devices should be avoided in APA reviews and reports
  • Suggestions and examples are given for each stylistic issue

APA Stylistics: Things to Avoid

  • Identifies the risk of bias in language concerning gender, race, disability, and sexuality when writing up research in APA fields
  • Provides links to APA's official guidelines on avoiding bias
  • Offers suggestions on finding alternatives to gendered pronouns and using different descriptors when identifying people in your research

APA Citations and Reference List

Perhaps the trickiest part to mastering APA Style is understanding the requirements for citing and listing secondary sources accurately. The following pages walk you through the details of writing citations and developing a reference page at the end of your paper. Read these guidelines carefully! It is important that you refer to your sources according to APA Style so your readers can quickly follow the citations to the reference page and then, from there, locate any sources that might be of interest to them. They will expect this information to be presented in a particular style, and any deviations from that style could result in confusing your readers about where you obtained your information.

In-Text Citations: The Basics

  • Addresses the basic formatting requirements of using the APA Style for citing secondary sources within the text of your essay
  • Provides guidance on how to incorporate different kinds of references to borrowed material, from short quotes to summaries or paraphrases

In-Text Citations: Author/Authors

  • Focuses on various details about referring to the authors of your sources within your essay, which can be difficult to do efficiently if the source has more than one author or has an unclear author (e.g. an organization)
  • Describes how to cite indirect quotes, electronic sources, and/or sources without page numbers

Footnotes and Endnotes

  • Recommends using footnotes or endnotes to avoid long explanations in the text
  • Covers two basic kinds of notes: bibliographic and digressive

Reference List: Basic Rules

  • Guides you through the general rules that apply to any reference list developed using APA Style
  • Covers everything from where the reference list appears to the capitalization of words in the titles of sources
  • Serves as a primer on formatting that will be followed in all of the following handouts on creating APA reference entries

Reference List: Author/Authors

  • Walks you through how to construct a reference entry for different text starting with a focus on author
  • Notes how the references are different depending on the number of authors or if there are multiple works by the same author

Reference List: Articles in Periodicals

  • Builds from the previous handout by looking specifically at how to refer accurately to a periodical source
  • Lists types of entries depending on the kind of journal (e.g. one paginated by volume), if the source is a magazine v. a newspaper, or the kind of article the source is (e.g. a letter to the editor)

Reference List: Books

  • Builds from the author handout by describing how to properly refer to book-length sources
  • Addresses both the basic format as well as requirements for those unique book sources that require you to note specific details, such as whether it is a translation or part of a multivolume work

Reference List: Other Print Sources

  • Offers a short list of other less common print sources you might be citing in your manuscript and how to construct references for them
  • Covers examples such as citing a source that is cited in another, or citing a government document

Reference List: Electronic Sources

  • Walks through the requirements and unique qualifications (see the Notes throughout the page) for constructing references for electronic sources
  • Covers sources from online periodicals and scholarly databases, to emails.

Reference List: Other Non-Print Sources

  • Focuses primarily on how to reference video and audio texts that are used as sources, from movie clips to sound recordings
  • Notes that personal communication (e.g. an interview or conversation) is not to be included in the reference list.

Junior researchers frequently wonder how many references should be included in their research papers. The common response? “As many as you need.” What exactly does that mean? While we admit there are very few hard-set rules regarding this issue, in this article, we will try to provide more concrete guidelines that will help you assess whether you have enough references in your paper.

Before we do so, let us briefly explain why references matter and whether the number of references you include can project certain perceptions about the quality of your work. There is such a thing as having too many or too few.

Why references are necessary

References show that you have carefully reviewed the relevant literature and are now contributing something novel to the academic community. You establish authority and credibility when you can critically assess other literature and distinguish your findings from previous works (if any exist). We emphasize “critically assess” in the last sentence because references are only as good as you apply them to your research. Therefore, the famous adage “quality over quantity” is the key to deciding how many references are sufficient.

Quantity can matter due to perceptions

We would be remiss if we didn’t tell you that being at either extreme (having too few or too many references) can reflect poorly on your intellectual aptitude and your study’s validity. Here’s why.

  • If you don’t have enough references, particularly on a topic familiar to a wide audience, readers may think that you haven’t done enough research into existing literature. Surely someone else has thought about related topics or used similar techniques. If you’re sloppy in conducting your diligence, readers will wonder whether your paper is worth reading. What’s novel and valuable about your paper? Were you just as sloppy with conducting your study? The answers to these questions need to be evident. Additionally, readers might be concerned that you may have plagiarized by failing to properly cite information. Unless you’re John Nash, who cited only two texts in his seminal 26-page PhD thesis (one of which was to his prior work), ensure that you’ve properly researched the relevant papers and included appropriate citations!
  • If you have too many references, readers may wonder if you did any original research at all. Unless you’re writing a literature review, your paper’s primary focus should be on your investigation and findings. Don’t bury your hard work under strings of citations and discussion regarding other works. Show your readers what you’ve discovered and how the new information you present fits into or departs from the academic community’s current understanding of your topic.

Additionally, let us highlight the difference between the number of references versus citations. References are the source materials; therefore, each reference should be listed only once in your references section. Citations are meant to identify the source of the information you use in your paper. You can cite a reference multiple times. Therefore, the number of citations you have is typically larger than the number of references. The opposite situation should never happen!

Key factors influencing the number of references you use

The following are some of the many factors that may influence the number of references you use:

  1. The number of references required for a paper will depend largely on your work’s purpose. For example, literature and systematic reviews are surveys of existing studies. Therefore, their reference lists will be more exhaustive than those of research papers whose primary focus is the current authors’ findings. Indeed, if you examine many journals’ author guidelines, you’ll note that journals have a higher maximum reference limit for review articles than original research papers.
  2. The length of your reference list will also depend on your researchpaper’s subject matter. For example, if you are writing about a less studied field, such as a subfield of neuroparasitology, you may discover that there aren’t many papers to cite. Similarly, newer fields will have fewer published papers that can be referenced. If you find yourself in this situation, review the references used by relevant current literature and see if you can expand your research, and thus your reference list, with valuable content from there.
  3. Another factor will be your institution or journal’s requirements. If you are preparing a dissertation or thesis, double-check your department’s requirements. While rare, they may have specific limits. More commonly, journals restrict the number of references due to printing constraints.
  4. It may happen that you don’t have access to certain literature that could have served as a reference. In such a situation, you may wish to look for an institution that may be able to provide you access to that literature for the purposes of reviewing the content.
  5. Given that more papers are being published than ever before in most fields, it is likely that reference lists will grow longer simply because there are more data points and discussions available to cite. Keep track of changes to the size of reference lists in publications related to your field.
  6. Finally, a paper’s length bears some correlation to the number of references.

The “right” number of references

Below, we provide tips on how to decide if you have enough resources. We also provide some general reminders on how to effectively use references. After all, references are meant to enhance your paper while still maintaining your research as the focal point.

Let journals be your guides

  • One way to gauge how many references you should have is to survey academic journals for your article type in your field. Review their author guidelines for limits on the number of references for your article type, and make sure your reference list complies with those journal restrictions.
  • Read recent articles relevant to your topic; check how many references other authors have included in their papers for the same article type as yours, and how frequently those works were cited per page.
  • Keep in mind that the above methods will give you an estimate of how many references you should include but will not tell you how many citations you’ll need per page. The latter is impossible to state simply because certain sections may have no citations at all (the results section, for example).

Statistics regarding the number of references and citations

To give you a general idea, the following are some estimates from a couple of studies that examined the citation characteristics of articles published in various disciplines.

According to Milojević’s study encompassing research in the fields of astronomy, mathematics, robotics, ecology, and economics, the highest and average number of references per article page were as follows:

  • Ecology: highest, ~58; average reference per page, 6;
  • Math and robotics: highest, ~28; average reference per page, <1; and
  • Economics: highest, ~ 32; average reference per page, >1 but <2.

The above findings were based on data compiled from the first 20 years of the author’s research. Since then some fields have increased the number of references. Thus, make sure to examine your target journal’s most recent and relevant publications for a better idea of how many references to include based on the specific type of article you plan to write.

In another study by Falagas et al. (2013), medical journals averaged 29 references for articles that were 7.88 pages long (as printed in journals).

Finally, although the sample size was small (63 journals), Gali Halevi observed the following citation trends of a broader range of disciplines.

  • The average number of references per article was the highest for the social sciences, physics, and astronomy, and arts & humanities (roughly 54 references per article).
  • On the other hand, health professions and earth and planetary sciences had the fewest references per article at an average of 8 and 17 references, respectively.
  • Math and engineering averaged at roughly 29 references per article.
  • Biochemistry, genetics and molecular and other biological sciences averaged at 51.
  • Hard and natural sciences more frequently cited recent literature while social sciences and math were likely to include older sources.

Note that the Halevi study is limited in size, fails to factor in article type and does little to account for variances across different fields and journals. For example, it is possible that more review articles could have been reviewed for certain fields than others. With that said, we provide the above information to provide a rough estimate.

At the end of the day, please keep in mind the requirements of your institution or target journal and the general trends for your specific article type (by examining the most recent relevant publications).

For additional information regarding journal restrictions on the number of references, click here.

Some dos and don’ts of using references

  • Don’t repeat references within a reference list.
  • Don’t repeatedly cite yourself. Make sure to balance your discussion with external literature citations.
  • Be careful about citing old references. The rule of thumb is to go back at most five to six years. Exceptions to this rule should be reserved for “seminal” works relevant to explaining what prompted your research. Roughly 85% of all cited works should be less than five years old.
  • Be careful not to cite several references in one place without discussing the relevance of each work to your research. In other words, don’t say, “We referred to previous studies in this field (1-7)” unless you later explain how each of reference #s 1-7 apply to your discussion.
  • Confirm the quality of the work you cite. Are there any ethical issues regarding the paper that would disqualify it as a good source? Do your references come from reputable sources such as respected journals rather than random blogs and website links? Remember that your analysis is only as good as the verifiable information you use to conduct your research.
  • One of the main purposes of citing existing literature is to show the “knowledge gap” regarding your topic. Therefore, make sure the works you reference naturally lead readers to wonder about the research question you address in your paper. To explain further, think about your favorite fictional story. A successfully written story only reveals the background information needed for the reader to follow along in the story. You’ll rarely see an author waste time writing about how the main character stubbed his toe one day while going to work unless that event relates to an important aspect of the story. Similarly, the references you cite should support the story building you create in your research paper.
  • Don’t completely ignore the paper that could disprove your hypothesis. You want to show objectivity and that you took a balanced and unbiased approach to conducting your research. Mention the potentially conflicting evidence and explain why you believe it is flawed or inapplicable to your research.
  • In qualitative research papers, you may have fewer references.
  • Anything you cite in your paper should be listed in the references section. Anything listed as a reference should have been quoted or paraphrased in the text. If either rule is violated, something is wrong.
  • Finally, remember that a paper will typically have more citations in the Introduction and Discussion sections than in other parts.

Additional reading

  • Stefanie Haustein. Chapter 2 of Multidimensional Journal Evaluation: Analyzing Scientific Periodicals Beyond the Impact Factor. (De Gruyter Saur, 2012).
  • Gali Halevi, “Citation characteristics in the Arts & Humanities.” [Note this paper involved a limited sample size and did not factor in article type.]
  • Staša Milojević, “How are academic age, productivity and collaboration related to citing behavior of researchers?”
  • Falagas, Matthew E., Zarkali, Angeliki, Karageorgopoulos, Drosos E., Bardakas, Vangelis, and Mavros, Michael N., “The Impact of Article Length on the Number of Future Citations: A Bibliometric Analysis of General Medicine Journals.”

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