Proper citation is non-negotiable in academic writing. It gives credit to original authors, allows readers to verify your sources, and protects you from plagiarism.

This guide covers everything you need to know about citing sources, including APA, MLA, and Chicago formats with clear examples.

• Gives credit to original researchers
• Avoids plagiarism (a serious academic offense)
• Shows your research is thorough

• Supports your claims with evidence
• Allows verification of your sources
• Demonstrates expertise in your field

• Enables further reading on topics
• Shows the conversation you're joining
• Provides context for your arguments

Every citation has two parts:

• Appears in the body of your paper
• Brief reference (author, date, page)
• Signals that information came from a source

• Appears at the end of your paper
• Complete publication information
• Listed in "References," "Works Cited," or "Bibliography"

Both parts are required—in-text citations point to full references.

Used in: Sciences, psychology, social sciences, education

One Author:

Research shows significant effects (Smith, 2024).
Smith (2024) found significant effects.

Two Authors:

(Smith & Jones, 2024)
Smith and Jones (2024) found...

Three or More Authors:

(Smith et al., 2024)
Smith et al. (2024) demonstrated...

Direct Quote:

"Exact words from source" (Smith, 2024, p. 45).
Smith (2024) stated, "exact words" (p. 45).

Multiple Sources:

Several studies confirm this (Jones, 2023; Smith, 2024).

Journal Article:

Author, A. A., & Author, B. B. (Year). Title of article. Journal Name,
    Volume(Issue), Page–Page. https://doi.org/xxxxx

Example:

Smith, J. A., & Johnson, M. B. (2024). Effects of sleep on memory
    consolidation in adolescents. Journal of Cognitive Neuroscience,
    36(4), 123–145. https://doi.org/10.1162/jocn_a_01234

Book:

Author, A. A. (Year). Title of book: Subtitle. Publisher.

Example:

Johnson, R. T. (2023). Research methods for beginners: A practical
    guide. Academic Press.

Book Chapter:

Author, A. A. (Year). Title of chapter. In E. E. Editor (Ed.), Title
    of book (pp. xx–xx). Publisher.

Website:

Author, A. A. (Year, Month Day). Title of page. Site Name. URL

Example:

Centers for Disease Control. (2024, January 15). Teen mental health.
    CDC. https://www.cdc.gov/teen-mental-health

No Author:

Title of article. (Year). Publication Name. URL

No Date:

Author, A. A. (n.d.). Title. URL

• Title: "References" (centered, bold)
• Alphabetical by first author's last name
• Double-spaced
• Hanging indent (first line flush left, subsequent lines indented 0.5")
• DOIs when available

Used in: Literature, humanities, arts

One Author:

Research shows significant effects (Smith 45).
Smith found significant effects (45).

Two Authors:

(Smith and Jones 45)

Three or More Authors:

(Smith et al. 45)

No Page Number:

(Smith)
Smith argues that...

No Author:

("Title of Article" 45)

Multiple Sources:

(Smith 45; Jones 67)

Journal Article:

Last, First. "Title of Article." Journal Name, vol. #, no. #, Year,
    pp. #–#.

Example:

Smith, John. "Memory and Learning in Adolescents." Cognitive Psychology
    Quarterly, vol. 42, no. 3, 2024, pp. 234–256.

Book:

Last, First. Title of Book. Publisher, Year.

Example:

Johnson, Rebecca. Research Methods for Students. Academic Press, 2023.

Website:

Last, First. "Title of Page." Website Name, Publisher, Day Month Year,
    URL.

Example:

Smith, John. "Understanding Research Methods." Research Hub, Research
    Foundation, 15 Jan. 2024, www.researchhub.org/methods.

No Author:

"Title of Article." Website Name, Day Month Year, URL.

• Title: "Works Cited" (centered)
• Alphabetical by first element (usually author's last name)
• Double-spaced
• Hanging indent
• Access date optional for online sources

Used in: History, some sciences, publishing

Chicago has two systems:

Uses footnotes/endnotes plus bibliography.

Footnote (First Reference):

1. John Smith, Research Methods (New York: Academic Press, 2024), 45.

Footnote (Subsequent):

2. Smith, Research Methods, 67.

Bibliography:

Smith, John. Research Methods. New York: Academic Press, 2024.

Similar to APA.

In-Text:

(Smith 2024, 45)

Reference List:

Smith, John. 2024. Research Methods. New York: Academic Press.

APA:

In-text: ("Title of Article," 2024)
Reference: Title of article. (2024). Publication. URL

MLA:

In-text: ("Title of Article" 45)
Works Cited: "Title of Article." Publication, 2024, pp. 45–50.

APA:

In-text: (Smith, n.d.)
Reference: Smith, J. (n.d.). Title. URL

MLA:

Works Cited: Smith, John. "Title." Website, URL. Accessed 15 Jan. 2024.

APA (same year):

(Smith, 2024a)
(Smith, 2024b)

MLA:

Use title to differentiate: (Smith, "First Article" 45)

Try to find the original, but if you can't:

APA:

In-text: (Original Author, as cited in Smith, 2024)
Reference: Only list Smith (the source you read)

MLA:

In-text: (qtd. in Smith 45)
Works Cited: Only list Smith

APA:

In-text: (J. Smith, personal communication, January 15, 2024)
Reference: Not included (can't be retrieved by readers)

APA:

Author/Creator. (Year, Month Day). Title [Video]. Platform. URL

Example:

TED. (2024, March 1). The science of learning [Video]. YouTube.
    https://www.youtube.com/watch?v=xxxxx

• Direct quotes
• Paraphrased ideas from sources
• Statistics and data
• Specific facts that aren't common knowledge
• Others' theories, methods, or frameworks
• Images, figures, or tables from sources

• Common knowledge ("The Earth orbits the Sun")
• Your own original ideas and analysis
• Your own data and observations
• Generally known facts in your field

Cite it. Over-citation is better than plagiarism.

• Copying text without quotes and citation
• Paraphrasing without citation
• Using someone's ideas without credit
• Self-plagiarism (reusing your own work without disclosure)
• Buying or copying someone else's paper

1. Take Careful Notes

• Mark direct quotes clearly in your notes
• Always record source information
• Distinguish your ideas from source ideas

2. Paraphrase Properly

• Change both words AND sentence structure
• Don't just swap synonyms
• Still requires citation

3. Quote When Appropriate

• Use exact words with quotation marks
• Include page number
• Don't overuse quotes

Bad Paraphrase (Plagiarism):

Original: "Social media use correlates strongly with anxiety in teens." Bad: "Social media usage correlates significantly with anxiety in teenagers."

Good Paraphrase:

Original: "Social media use correlates strongly with anxiety in teens." Good: Research has found a significant relationship between how much time adolescents spend on social platforms and their reported anxiety levels (Smith, 2024).

Zotero (Free)

• Saves sources from browser
• Generates citations automatically
• Works with Word and Google Docs

Mendeley (Free)

• Good for PDFs
• Social features
• Citation generation

EndNote (Paid)

• Powerful features
• Steep learning curve
• Common in academia

Use with Caution:

• Citation Machine
• EasyBib
• BibMe

Warning: Always verify auto-generated citations. They often contain errors.

1. Use a citation manager to organize
2. Generate citations with the tool
3. Always check for accuracy
4. Format according to your style guide

Problem: Mixing APA and MLA Fix: Choose one style and use it throughout

Problem: "Direct quote" (Smith, 2024). Fix: "Direct quote" (Smith, 2024, p. 45).

Problem: Reference list without proper indentation Fix: First line flush left, subsequent lines indented

Problem: John Smith (2024) Fix (APA): Smith (2024) or J. Smith (2024)

Problem: Not including DOI when available Fix: Always include DOI for journal articles

Problem: Wrong elements italicized Fix: Italicize book titles and journal names, not article titles (APA)

Problem: In-text citation with no matching reference Fix: Every in-text citation needs a full reference (and vice versa)

• Every source has an in-text citation
• Format is consistent (APA, MLA, or Chicago)
• Direct quotes have page numbers
• Multiple authors handled correctly
• All in-text citations match reference list

• Title is correct ("References" for APA, "Works Cited" for MLA)
• Alphabetical order by first author
• Hanging indent applied
• Double-spaced
• All required elements included
• DOIs included when available
• URLs are active and correct
• Every reference has an in-text citation

Proper citation takes practice. Expert guidance helps you get it right.

The YRI Fellowship provides:

• Writing Support: Feedback on citations and formatting
• Multiple Reviews: Catch errors before submission
• Publication Guidance: Learn journal-specific requirements
• 1:1 Mentorship: Experts answer your questions

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Which citation style should I use? Use what your instructor, competition, or target journal requires. For science fairs, APA is most common for sciences. If not specified, APA is a safe choice for STEM fields.

How do I cite a source I found in another source? Try to find and read the original source. If you can't, use "as cited in" (APA) or "qtd. in" (MLA) and only list the source you actually read in your references.

Do I need to cite common knowledge? No. Facts that are widely known don't need citations. However, if you're unsure whether something counts as common knowledge, cite it.

Can I use citation generators? Yes, but always verify the output. Generators frequently make errors, especially with unusual sources.

How many citations should my paper have? There's no fixed number, but every claim that isn't common knowledge or your own original idea needs a citation. A typical research paper has citations every 1-2 paragraphs.

What if a source has no author or date? Use the organization name as author, or "Anonymous" if truly unknown. Use "n.d." (no date) if no date is available.

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