Types of Citations in Writing for Researchers


When conducting research, most scientists would agree that properly citing sources is crucially important.

Using the right citation style lends credibility and enhances the scholarly impact of your work. In this article, you'll discover the key citation formats used in scientific writing and learn to apply them for research excellence.

We provide an in-depth exploration of APA, MLA, Chicago, and IEEE styles, including when to use each and how to craft in-text citations and references. You'll also find comparative analyses and examples across citation styles to inform and simplify your formatting decisions.

Introduction to Citation Styles in Research Writing

Citations are a critical component of academic writing and scientific literature. They serve the important purposes of giving credit to original sources, allowing readers to locate those sources, and supporting claims made in research. Using proper citation styles lends credibility to papers and helps authors avoid accusations of plagiarism. This article will provide an overview of common citation styles used in research writing.

Understanding the Importance of Citations

Citations have several key functions in research writing:

  • Give credit to original sources of ideas, quotes, data, and other material used

  • Allow readers to easily locate the original sources referenced

  • Support factual claims made in the paper with credible external sources

  • Demonstrate the writer has conducted thorough research

  • Prevent plagiarism by making it clear which ideas are the author's own and which come from external sources

Accurately citing sources with a consistent citation style is crucial for establishing credibility as a researcher.

Overview of Citation Styles Examples

There are several widely used citation styles, with the most common being:

  • APA (American Psychological Association) - Used in psychology, education, and social sciences

  • MLA (Modern Language Association) - Used in humanities disciplines

  • Chicago/Turabian - Used in business, history, and fine arts

  • IEEE (Institute of Electrical and Electronics Engineers) - Used in computer science, engineering, and technology

The examples below demonstrate in-text citations in each of these major styles:

APA: (Smith, 2020) MLA: (Smith 25)
Chicago: (Smith 2020, 15) IEEE: [1]

There can be variations even within the same citation style depending on the type of source, number of authors, etc.

Selecting the Appropriate Citation Style

Choosing the right citation style depends on several factors:

  • Discipline - Styles may be standardized within fields. For example, APA in social sciences.

  • Publisher/journal guidelines - Specific styles may be required for submission.

  • Type of sources cited - Some styles work better for web, digital, or audiovisual sources.

Writers should clarify which style is most appropriate early in the writing process to allow for consistency.

Ethical Considerations in Citation Practices

Proper citation demonstrates respect for intellectual property and upholds ethical integrity:

  • Obtain permission when using lengthy quotes

  • Avoid over-citing sources to artificially inflate credibility

  • Guard against citation errors that could be seen as misrepresentation

  • Credit all contributing authors and researchers

By conscientiously citing sources, writers promote trustworthiness in research writing.

What are the 3 types of citations?

The three main citation styles used in academic writing are:

  1. APA (American Psychological Association)
    Used in education, psychology, sciences, etc. Includes author, date, page number.

  2. MLA (Modern Language Association) Used in humanities, literature, arts, etc. Includes author and page number.

  3. Chicago/Turabian
    Used in business, history, fine arts. Footnotes or endnotes format.

These three citation styles have different formats and rules for citing sources in research papers and manuscripts. Choosing the right one depends on your field of study.

APA is common in scientific papers published in journals. It uses parenthetical in-text citations with the author's last name, year, and page numbers. The full reference list is ordered alphabetically by authors' last names.

MLA is the standard for humanities and literature analysis essays. The in-text citations include the author and page in parentheses. The works cited page lists the references alphabetically by the authors' last names.

Chicago/Turabian is preferred for history, arts, and social sciences writing. Sources are cited through footnotes or endnotes with bibliographic information. It also necessitates a bibliography page.

Understanding these major academic citation styles, their formats, and appropriate applications in research writing is key to properly attributing sources. Consult the official style manuals for detailed guidelines.

What are the 4 methods of citation?

There are four main citation styles commonly used in academic writing:

  1. MLA (Modern Language Association): Commonly used in the humanities, literature, and arts. MLA citations include the author's last name and page number in parentheses.

  2. APA (American Psychological Association): Used most often in the social sciences. APA citations include the author's last name, year of publication, and page number in parentheses.

  3. Chicago: Used across disciplines, especially history. Chicago style citations use footnotes or endnotes that include the author's name, source title, publication details, and page number.

  4. AMA (American Medical Association): Used in medical and scientific writing. AMA citations include a superscripted number that corresponds to a numbered reference list.

While there are some minor variations, these four methods make up the significant majority of citation formats. Choosing the right one depends on your field of study and the requirements or preferences of publishers and institutions you write for. Adhering properly to citation guidelines is crucial for giving credit to sources and enabling readers to locate your references.

What is the difference between APA and MLA citations?

APA and MLA are two of the most common citation styles used in academic writing. Here is a quick overview of some of the key differences:

In-Text Citations

  • APA uses the author's last name and year of publication (Jones, 2019)

  • MLA uses the author's last name only (Jones)

Reference List

  • APA lists references alphabetically by author last name under the centered heading "References"

  • MLA lists works cited alphabetically by author last name under the centered heading "Works Cited"


  • APA: Periods separate each element, use ampersands (&) in multiple author listings

  • MLA: Commas separate elements, use the word "and" in multiple author listings


  • APA: Sentence case capitalization for titles

  • MLA: Title case capitalization for titles

Page Numbers

  • Both styles require page numbers for direct quotes in in-text citations

  • APA includes p. or pp. before page numbers

  • MLA does not use p. or pp.

The key is to be consistent in following the rules of the selected citation style. Check official style guides for comprehensive formatting guidelines.

How do you identify a citation style?

There are several common citation styles used in academic and scientific writing. Here are some tips to help identify which citation style is being used:

Look for parenthetical in-text citations

If you see citations in parentheses within the text, such as (Smith, 2022) or [Smith, 2022], this indicates a citation style like APA or MLA.

Check the references or works cited page

Look at the format of the entries in the references or works cited page at the end. This will give you clues about the style. For example, if the year follows the author name, it is likely APA style.

Note formatting details

Pay attention to things like capitalization, italics, punctuation between elements, the order of elements, and abbreviations. These small details can indicate citation styles like MLA, APA, Chicago, IEEE, etc.

Consider the discipline

Some disciplines have preferred styles. For example, APA is common in psychology and social sciences; MLA is common in the humanities; Chicago is used in history and some humanities; IEEE is used in computer science and engineering.

When in doubt, ask!

If you are submitting to a journal or professor and are unsure of the citation style, don't hesitate to ask for clarification. Adhering to the expected style is important.

Identifying citation styles takes practice, but paying attention to these tips will help! Let me know if you need any other advice on deciphering citation formats.

APA Citation Style Overview

APA style is commonly used in the social sciences and education. It provides guidelines for in-text citations and reference lists.

Basics of APA In-Text Citations

APA in-text citations include the author's last name, year, and page number in parentheses: (Smith, 2022, p. 5). Key elements:

  • Author's last name

  • Publication year

  • Page number for direct quotes

For example:

"APA style helps create consistency in scientific writing" (Jones, 2021, p. 15).

If the author's name is included in the sentence, only the year and page number are needed:

Jones (2021, p. 18) states that "using APA makes papers easier to comprehend."

Formatting the APA Reference List

The APA reference list contains full publication details alphabetically by authors' last names. The general format is:

Author, A. A., Author, B. B., & Author, C. C. (Year). Title. Publisher.

For example:

Smith, J., Jones, R., & White, A. (2022). Using APA Style for Scientific Writing. Science Publishers.

Key elements:

  • Author names in order they appear on publication

  • Publication year

  • Title italicized

  • Publisher name

The reference list should be on a new page at the end of the paper.

APA Citation Examples for Common Source Types


Watson, J. D. (1968). The double helix. Simon & Schuster.

Journal Article:

Smith, A. J., & Jones, B. (2019). Using APA style for research papers. Journal of Citation Styles, 15(2), 35–47.


National Library of Medicine. (2022, January 15). APA style. https://www.nlm.nih.gov/bsd/uniform_requirements.html

See the APA Style website for more examples.

Citing Digital Media and Non-Traditional Sources in APA

To cite online videos, social media posts, and other digital content:

  • Provide the author name/username and post date

  • Link directly to the source when possible

  • Describe the format in square brackets - [Tweet], [Video], etc.

For example:

Gates, B. [BillGates]. (2022, February 2). Whether you're a student or a professional, APA style makes scientific writing more clear and consistent [Tweet]. Twitter. https://twitter.com/BillGates/status/1488971057127956480

Use best judgment in citing emerging source types not covered in the traditional APA guidelines. The goal is to credit original creators and enable readers to find the content.

MLA Citation Style Explained

MLA style is often used in the humanities. It features brief in-text citations pointing to full source details on a separate works cited page.

Crafting MLA In-Text Citations

MLA in-text citations contain just the author's last name and page in parentheses:

(Smith 5)

These brief references point readers to the full source details provided in the works cited list at the end of the paper.

Assembling the MLA Works Cited Page

The MLA works cited page includes full bibliographic details on all sources referenced in the paper. Entries are:

  • Arranged alphabetically by the authors' last names

  • Displayed in hanging indent format

  • Include elements like author, title, publisher, etc.

Formatting example:

Smith, John. Research Methods for Humanities. Oxford UP, 2022.

MLA Citation Examples for Diverse Sources

MLA format can accommodate citations for:

  • Books: Last name, First name. Title. Publisher, Year.

  • Articles: Last name, First name. "Title." Journal, Vol. #, No. #, Year, pages.

  • Websites: Last name, First name. "Title." Website Name, Day Month Year, URL.

Adapting MLA Citations for Digital Formats

To cite e-books, databases, or other digital formats in MLA style:

  • Provide source the same way as print

  • Add relevant details like DOI, stable URLs, access dates

This ensures proper credit even for electronic resources.

Navigating Chicago Style Citation

The Chicago style has two systems: notes and bibliography or author-date. It covers various disciplines in the sciences and humanities.

Utilizing the Notes and Bibliography System

The notes and bibliography system uses footnotes or endnotes to cite sources. When you cite a source, you add a superscript number at the end of the sentence that corresponds to a footnote or endnote containing the full publication details. This allows readers to easily find the source information in the notes section.

Some key things to know when using the notes and bibliography system:

  • Place note numbers at the end of the clause or sentence where the source is referenced, before the punctuation.

  • Number notes sequentially throughout the paper.

  • Provide full publication details in the first note for each source (subsequent notes can use shortened versions).

  • Compile all footnotes/endnotes in a "Notes" section.

  • Include a separate "Bibliography" section listing all cited sources in alphabetical order by authors' last names.

Implementing the Author-Date System

The author-date system uses parenthetical in-text citations with the author's last name, year of publication, and page numbers (if applicable). The in-text citations connect to a reference list at the end organized alphabetically by author's last name.

Key things to know about the author-date system:

  • Place parenthetical citations inside closing punctuation.

  • No note numbers - only author last name, year, and page in parentheses.

  • Reference list contains full publication details for each in-text citation.

  • List references alphabetically by authors' surnames.

  • Multiple works by same author are organized chronologically, earliest to latest.

Chicago Style Citation Examples

Book (notes and bibliography):

  1. John K. Smith, Example Book Title (Chicago: Example Press, 2022), 65.

Smith, John K. Example Book Title. Chicago: Example Press, 2022.

Journal Article (author-date):

Research shows connection between diet and disease (Smith 2021, 18).

Smith, John A. 2021. "Connection between Diet and Disease." Example Journal 12(3): 14-28.

Website (notes and bibliography):

  1. "Example Web Page," Example Organization, accessed March 1, 2022, https://www.example.org.

Citing Unconventional Materials in Chicago Style

Chicago style provides guidelines for referencing less conventional source types like personal communications, archival documents, and interviews:

  • Personal communications: Include initials and last name in text only, not references.

  • Interviews: Cite in notes only, no bibliography entry. Provide interview details like interviewee, interviewer, location, and date.

  • Archival materials: Provide collection name, box/folder numbers, name and location of archive, and full date in note and bibliography entry.

Formatting can vary based on item type, but goal is to give readers enough information to locate the source.

Understanding IEEE Citation Style

The IEEE style is widely used in electrical, electronic, computing, and engineering publications. It emphasizes numbered in-text citations matched to entries in a reference list.

Fundamentals of IEEE In-Text Citations

IEEE in-text citations feature bracketed reference numbers linked to full source details in the reference list: [1]. These numbers directly correspond to the numbered entries in the reference list. The numbers are ordered based on first appearance in the text.

Some key rules for IEEE in-text citations:

  • Place citation numbers in square brackets, like this [1].

  • Cite sources in numerical order based on first appearance.

  • Use numbers for both in-text citations and reference list entries.

  • Cite a source every time you reference it, using the same number each time.

  • Place citation numbers outside periods and commas, and inside colons and semicolons.

Compiling the IEEE Reference List

The IEEE reference list contains numbered entries with complete publication specifics for each corresponding in-text citation.

Key components of an IEEE reference list entry:

  • Author names formatted last name first initials only

  • Full article, book, or report titles in quotation marks

  • Journal or book titles in italic font

  • Volume, issue, and page numbers as applicable

  • Online sources require URLs or DOIs

List entries numerically in the order they first appear in-text. Include all sources cited in the document.

Examples of IEEE Citations for Technical Documents

Conference paper:

[1] J. K. Author, "Title of conference paper," presented at the Abbreviated Conference Name, City of Conference, Abbrev. State, Year.

Industry standard:

[2] Title of Standard, Standard number, Year.


[3] J. K. Inventor, "Title of patent," U.S. Patent x xxx xxx, Abbreviated Month, Day, Year.

Referencing Online Sources in IEEE Format

Online journal article:

[4] J. K. Author, "Title of journal article," Abbreviated Journal Title, vol. x, no. x, pp. xxx-xxx, Abbrev. Month, Year. doi: or URL.

Online database:

[5] Title of Content, Database Name, Year, URL (accessed Abbrev. Month, Day, Year).


[6] J. K. Developer, Title of Software, Version Number, Company, Year, Software URL.

Comparative Analysis of Citation Styles

Citations serve a vital role in research writing by crediting sources of information and enabling readers to verify claims. However, various citation styles exist with slight differences in format, punctuation, and organization. Choosing the right one depends on your field of study and target publication.

Differences Between APA, MLA, and Chicago Styles

The three most common citation styles have unique formats:

  • APA (American Psychological Association): Used in education, psychology, sciences. Includes author, year, and page number in in-text citations. Lists references alphabetically by author's last name.

  • MLA (Modern Language Association): Used in humanities and liberal arts. Mentions author and page in in-text citations. Organizes works cited alphabetically by author.

  • Chicago: Two formats - Notes/Bibliography and Author-Date. Used in history, arts, literature. Includes footnotes/endnotes and bibliographies.

Choosing the Right Style for Your Research

Select citation styles based on:

  • Discipline - Styles have conventions in different fields.

  • Target journal - Check the author guidelines.

  • University style guide - Some institutions mandate a style.

  • Assignment rubric - Follow instructor preferences.

Regardless of style, cite sources ethically and consistently.

Examples of Types of Citations in Writing Across Styles

A book chapter cited in different formats:

- In-text: (Krasner & Pope, 2018) 
- References: Krasner, J. & Pope, N. (2018). Chapter 7: Cognitive behavioral therapy. In J.L. Levenson (Ed.), *Handbook of Behavior Therapy* (pp. 97-113). ABC Publishers.  

- In-text: (Krasner and Pope 115)
- Works cited: Krasner, James, and Nicholas Pope. "Cognitive Behavioral Therapy." *Handbook of Behavior Therapy*, edited by Levenson John L., ABC Publishers, 2018, pp. 97-113.  

Chicago Author-Date
- In-text: (Krasner and Pope 2018, 115)
- References: Krasner, James, and Nicholas Pope. 2018. "Cognitive Behavioral Therapy." In *Handbook of Behavior Therapy*, edited by John L. Levenson, 97-113. ABC Publishers. 

Transitioning Between Citation Styles

When changing styles:

  • Learn the new style conventions and formats

  • Use citation generators to adapt sources

  • Check for accuracy - edit computer-generated citations

  • Review style guides like APA Manual for specifics

  • Ask a librarian if struggling with a difficult source

With practice, researchers can adeptly switch between major citation styles. The key is understanding the core elements of author, year, title, etc. that form all bibliographic entries.

Conclusion: Mastering Citation Styles for Research Excellence

Understanding key citation styles allows researchers to accurately reference sources, demonstrate credibility, and enable readers to locate published works. The major styles have distinct rules but share principles of ethical sourcing and attribution.

There are a few main types of citations used in academic and scientific writing:

  • APA Style - Used widely in psychology, education, and social sciences. Includes author, date, and other source details.

  • MLA Style - Common in humanities like literature and art. Focuses on author and page number.

  • Chicago/Turabian Style - Two closely related formats good for history and social sciences. Uses footnotes or endnotes.

  • IEEE Style - Follows numbered citation sequence. Common in technical fields like engineering and computer science.

  • AMA Style - Used often in medical and biological journals. Very similar to IEEE.

While each style has variations in order, punctuation, and formatting, they all aim to credit original sources clearly and consistently. Learning the dominant citation method in your field helps establish credibility through properly attributing quotes, data, and concepts. Accurate citations enable readers to efficiently locate your references to further analyze the source content.

With practice, researchers can master the key citation formats above to elevate their writing through ethical and transparent use of external sources. Focus first on the one or two styles used most in your discipline for the best return on effort. Understanding citation best practices ultimately improves the precision and persuasiveness of scientific communication.