Complete Guide to In-Text Citations

What Are In-Text Citations?

In-text citations are brief references embedded directly in your writing that connect a specific claim, quotation, or paraphrase to its full source in your bibliography, reference list, or works cited page. They serve two non-negotiable purposes: they give credit to the original author and they allow your reader to locate the source material independently.

Every major academic style guide mandates in-text citations. Getting them wrong can result in point deductions, manuscript rejections, or - in the worst case - allegations of plagiarism. The challenge is that each citation system has its own rules for formatting, punctuation, and author thresholds. This guide covers all five major systems in detail, with worked examples for every scenario you are likely to encounter.

If you want to skip the manual formatting entirely, the AllCitations generator produces both in-text citations and bibliography entries automatically. But understanding the underlying rules will make you a stronger writer and a more careful researcher.

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The Five Major Citation Systems

Before diving into examples, it helps to understand the landscape. Academic citation systems fall into five broad families:

• Author-date - Used by APA 7th edition and Harvard. The citation contains the author's surname and the year of publication.
• Author-page - Used by MLA 9th edition. The citation contains the author's surname and the page number, but not the year.
• Numeric - Used by IEEE and Vancouver. Sources are numbered in the order they appear (or alphabetically, depending on the style), and the citation is simply that number in brackets or parentheses.
• Notes-bibliography - Used by Chicago Manual of Style (17th edition) and Turabian. The citation takes the form of a footnote or endnote with a superscript number in the text.
• Author-date variant (CSE) - Used by the Council of Science Editors. Similar to APA but with subtle differences in punctuation and et al. thresholds.

Each system is explored below with 10 or more worked examples.

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Author-Date: APA 7th Edition

APA style is the dominant citation format in psychology, education, nursing, and the social sciences. The rules below come from the Publication Manual of the American Psychological Association, 7th Edition, primarily Chapter 8 ("Works Credited in the Text") and Chapter 9 ("Reference List").

One Author

Parenthetical: Cognitive load increases when students switch between tasks (Sweller, 2019).

Narrative: Sweller (2019) demonstrated that cognitive load increases when students switch between tasks.

Two Authors

Parenthetical: The results were replicated in a larger sample (Patel & Kim, 2021).

Narrative: Patel and Kim (2021) replicated the results in a larger sample.

Note the difference: use an ampersand (&) inside parentheses, but the word and in narrative citations. This rule is specified in APA Manual Section 8.17.

Three or More Authors

Parenthetical: Early intervention improved outcomes across all age groups (Torres et al., 2022).

Narrative: Torres et al. (2022) found that early intervention improved outcomes across all age groups.

APA 7 simplified the old rules: regardless of how many authors a work has, use only the first author's surname followed by "et al." from the very first citation onward (APA Manual Section 8.17). This is a change from APA 6, which listed up to five authors on first mention.

No Author

When no individual or group author is identified, use the first few words of the reference list entry (usually the title) in place of the author name.

Article or chapter title (in quotation marks): ("Climate Trends in the Arctic," 2023).

Book, report, or webpage title (in italics): (Global Emissions Report, 2023).

No Date

Parenthetical: The phenomenon was first described in the early literature (Harrison, n.d.).

Narrative: Harrison (n.d.) first described the phenomenon in the early literature.

The abbreviation n.d. stands for "no date" and is always lowercase (APA Manual Section 9.17).

Direct Quotes With Page Numbers

Direct quotations must always include a page number, paragraph number, or other locator (APA Manual Section 8.25).

Short quotation (fewer than 40 words): The researchers concluded that "the effect was robust across all conditions" (Sweller, 2019, p. 112).

Narrative form: Sweller (2019) concluded that "the effect was robust across all conditions" (p. 112).

No page number (e.g., a website): (Torres et al., 2022, para. 4) or (Torres et al., 2022, "Results" section).

Paraphrases

Page numbers are encouraged but not required for paraphrases in APA 7. If you are paraphrasing a long or complex work, including a page number helps your reader.

Without page number: Multitasking reduces performance on both tasks (Sweller, 2019).

With page number (recommended): Multitasking reduces performance on both tasks (Sweller, 2019, p. 108).

Multiple Sources in One Citation

When citing several works to support a single point, list them alphabetically by first author and separate them with semicolons.

(Harrison, n.d.; Patel & Kim, 2021; Sweller, 2019; Torres et al., 2022)

Secondary Sources ("As Cited In")

Use secondary sources sparingly. If you read about Smith's 2010 findings in Torres et al. (2022), cite it this way:

Parenthetical: The original experiment produced similar results (Smith, 2010, as cited in Torres et al., 2022).

Narrative: Smith (2010, as cited in Torres et al., 2022) produced similar results.

Only Torres et al. (2022) appears in your reference list, because that is the work you actually read (APA Manual Section 8.6).

Personal Communications

Emails, interviews, phone calls, text messages, and other non-recoverable sources are cited in text but do not appear in the reference list.

Parenthetical: The policy was revised in early 2024 (L. Nakamura, personal communication, January 14, 2024).

Narrative: L. Nakamura (personal communication, January 14, 2024) confirmed that the policy was revised.

Organization as Author

First citation: (World Health Organization [WHO], 2023).

Subsequent citations: (WHO, 2023).

For a deeper comparison between APA and MLA, see our article on APA vs. MLA: Which Citation Style Should You Use?.

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Author-Date: Harvard Style

Harvard referencing is not governed by a single manual; instead, it is a generic author-date system widely used in UK, Australian, and some European universities. Individual institutions publish their own Harvard guides, but the core conventions are stable.

One Author

(Smith 2020) or Smith (2020) argues...

Note: most Harvard guides omit the comma between author and year, unlike APA. Always check your institution's specific guide.

Two Authors

(Smith and Jones 2020) or (Smith & Jones 2020) depending on the institutional guide.

Three Authors

Some Harvard guides list all three on first citation: (Smith, Jones and Lee 2020), then shorten to (Smith et al. 2020).

Four or More Authors

(Smith et al. 2020) from the first citation.

The et al. threshold varies by institution. Many Harvard guides set it at four authors, compared to APA's threshold of three. Always verify your institution's specific requirements.

No Author

(Title of Work 2020) - use the title in italics for standalone works.

No Date

(Smith n.d.)

Direct Quotes

(Smith 2020, p. 34) - page numbers are mandatory for direct quotes.

Paraphrases

(Smith 2020) - page numbers optional but encouraged.

Multiple Sources

(Jones 2019; Smith 2020; Torres et al. 2021) - semicolons between sources, alphabetical order.

Secondary Sources

(Smith 2010, cited in Torres 2020)

Personal Communications

(L. Nakamura 2024, personal communication, 14 January) - not included in the reference list.

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Author-Page: MLA 9th Edition

MLA style is the standard in literature, languages, cultural studies, and parts of the humanities. The rules below are drawn from the MLA Handbook, 9th Edition, particularly Chapter 5 ("Documenting Sources").

One Author

Parenthetical: The novel's unreliable narrator destabilizes the reader's assumptions (García 87).

Narrative: García argues that the novel's unreliable narrator destabilizes the reader's assumptions (87).

MLA does not use a comma between the author and the page number, nor does it use "p." or "pp." before the number.

Two Authors

Parenthetical: (Smith and Jones 112).

Narrative: Smith and Jones note that "the imagery recurs in every chapter" (112).

MLA always uses and, never an ampersand.

Three or More Authors

Parenthetical: (Torres et al. 203).

Narrative: Torres et al. describe the pattern as "unmistakable" (203).

MLA 9 adopted the et al. rule for three or more authors, aligning with APA 7.

No Author

Use the title. Shorten long titles to the first noun phrase.

Article: ("Climate Trends" 14).

Book: (Global Emissions 14).

No Page Number

For web sources or other works without fixed page numbers, omit the page number entirely.

Parenthetical: (García).

Narrative: García explores how the unreliable narrator destabilizes assumptions.

If the source uses paragraph numbers, you may write (García, par. 7). If the source uses numbered sections, you may write (García, sec. 3). See MLA Handbook Section 5.2.

Direct Quotes

Short quotation: The author calls the pattern "unmistakable in its regularity" (Torres et al. 203).

Block quotation (more than 4 lines of prose or 3 lines of verse): Indent the entire block one-half inch, do not use quotation marks, and place the parenthetical citation after the closing period.

Paraphrases

Page numbers are strongly recommended for paraphrases in MLA so the reader can verify the claim.

The imagery pattern repeats across every chapter (Torres et al. 200-210).

Multiple Sources in One Citation

Separate with semicolons: (García 87; Torres et al. 203).

Secondary Sources ("Qtd. In")

MLA uses the abbreviation qtd. in (quoted in):

Parenthetical: (Smith, qtd. in Torres et al. 210).

Only the source you actually consulted (Torres et al.) appears in the works cited list.

Indirect Sources (No Page Number, Web)

(García) - simply the author's last name if no locator is available.

For help generating MLA citations for websites, see our guide on How to Cite a Website in APA 7, which also covers MLA comparisons, or jump directly to the MLA 9 citation generator.

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Numeric: IEEE and Vancouver

Numeric systems replace author names with numbers. They are common in engineering, computer science, medicine, and the natural sciences.

IEEE Style

IEEE citations follow the order of appearance in the text. Each source receives a number in square brackets the first time it is cited, and that same number is reused for all subsequent citations of the same source. Rules are detailed in the IEEE Editorial Style Manual.

Basic citation: Machine learning models have shown promise in medical imaging [1].

With page number: The algorithm achieved 97% accuracy on the benchmark dataset [1, p. 42].

Multiple separate sources: Several studies confirm this trend [1], [3], [5].

Consecutive sources: The literature broadly supports this finding [1]-[5].

Non-consecutive and consecutive combined: [1], [3]-[7], [10].

Narrative form: In [1], the authors demonstrated that machine learning models show promise.

Two or more sources, same bracket: [1, 3, 5] - some IEEE publications allow this compressed form; check the target journal's guidelines.

Secondary source: IEEE does not have a formal "as cited in" mechanism. Best practice is to locate and cite the original source directly.

No author: The number system means the in-text citation looks the same regardless of authorship. The reference list entry handles the author information.

Personal communications: Cite as a footnote rather than a numbered reference, per the IEEE Editorial Style Manual.

Vancouver Style

Vancouver (also called the Uniform Requirements style) is used in biomedical and health science journals. It is maintained by the International Committee of Medical Journal Editors (ICMJE).

Basic citation: The treatment reduced inflammation within 48 hours (1).

Superscript variant: The treatment reduced inflammation within 48 hours.^1 - Many journals prefer superscript numbers. Check your target journal.

Multiple sources: (1, 3, 5) or (1-5) for consecutive.

With page number: (1, p. 233).

Three or more authors in the reference list: List up to six authors, then use "et al." - but this only affects the reference list, not the in-text number.

Narrative form: As demonstrated in reference (1), the treatment reduced inflammation.

Secondary sources: Like IEEE, Vancouver strongly discourages secondary citations. Locate the original source whenever possible.

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Notes-Bibliography: Chicago and Turabian

The Chicago Manual of Style (17th edition), Chapter 14 ("Notes and Bibliography"), describes a footnote/endnote system used widely in history, philosophy, religion, and parts of the humanities. Turabian's A Manual for Writers is the student-focused companion to Chicago.

First Citation - Full Note

The first time you cite a source, provide a complete note:

1. Margaret Chen, The Architecture of Memory (Chicago: University of Chicago Press, 2021), 145.

Subsequent Citations - Shortened Note

After the first citation, use the author's last name, a shortened title, and the page number:

2. Chen, Architecture of Memory, 150.

Ibid.

When the same source is cited in two consecutive notes, you may use "Ibid." (from the Latin ibidem, meaning "in the same place"):

3. Ibid., 152.

If the page number is also the same, use "Ibid." alone without a page number. Chicago 17th edition notes that "Ibid." is optional - you may always use the shortened form instead (Chicago Manual Section 14.34).

One Author

4. David Park, "Rethinking Urban Spaces," Journal of Modern Architecture 12, no. 3 (2023): 78.

Two Authors

5. David Park and Sarah Lin, "Rethinking Urban Spaces," Journal of Modern Architecture 12, no. 3 (2023): 78.

Three Authors

6. David Park, Sarah Lin, and James Okafor, "Rethinking Urban Spaces," Journal of Modern Architecture 12, no. 3 (2023): 78.

Four or More Authors

Use the first author followed by "et al.":

7. Park et al., "Rethinking Urban Spaces," 80.

On first citation, Chicago recommends listing all authors in the full note if there are up to ten. For eleven or more, list the first seven followed by "et al." (Chicago Manual Section 14.76).

No Author

8. "Global Emissions Report 2023" (Geneva: United Nations Environment Programme, 2023), 12.

No Date

9. Robert Harrison, Theories of Perception (London: n.p., n.d.), 34.

Direct Quotes

Always include a page number or other locator in the note when quoting directly.

Multiple Sources in One Note

10. Chen, Architecture of Memory, 145; Park and Lin, "Rethinking Urban Spaces," 78.

Secondary Sources ("Quoted In" or "Cited In")

11. James Smith, "Original Study," quoted in Margaret Chen, The Architecture of Memory (Chicago: University of Chicago Press, 2021), 160.

Personal Communications

Personal communications may be cited in a note but are typically omitted from the bibliography:

12. Laura Nakamura, email message to author, January 14, 2024.

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Author-Date Variant: CSE (Council of Science Editors)

CSE style, governed by Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers (8th edition), offers three documentation systems: citation-sequence, citation-name, and name-year. The name-year system is an author-date format with some differences from APA.

One Author

(Harrison 2020) - no comma between author and year.

Two Authors

(Patel and Kim 2021) - use "and," not an ampersand.

Three or More Authors

(Torres et al. 2022) - CSE uses "et al." for three or more authors from the first citation.

No Author

Use the organization name or the first word(s) of the title: ([WHO] 2023) or (Global Emissions 2023).

No Date

CSE does not use "n.d." the same way APA does. If the date is uncertain, use a question mark: (Harrison 2020?) or note the approximation in the reference list.

Direct Quotes

(Harrison 2020, p. 34) - include a page number for direct quotations.

Paraphrases

(Harrison 2020) - page number optional.

Multiple Sources

(Harrison 2020; Patel and Kim 2021; Torres et al. 2022) - semicolons, alphabetical.

Secondary Sources

CSE discourages secondary citations. If unavoidable: (Smith 2010, as cited in Torres et al. 2022).

Personal Communications

Cite in text only: (L. Nakamura, personal communication, 2024). Not listed in the reference list.

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Master Comparison Table

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When to Cite vs. When Not To

One of the most common questions students ask is: "Do I need to cite this?" The answer depends on whether the information counts as common knowledge.

What Is Common Knowledge?

Common knowledge is information that is widely accepted, easily verified, and not the product of original research. You do not need a citation for common knowledge.

No citation needed:

• Water boils at 100 degrees Celsius at sea level.
• The Declaration of Independence was signed in 1776.
• Tokyo is the capital of Japan.

Citation needed:

• A 2023 study found that 68% of Tokyo residents support expanded cycling infrastructure (Tanaka, 2023).
• The average global temperature rose by 1.1 degrees Celsius between 1850 and 2020 (IPCC, 2021).
• Some historians argue that economic factors were more decisive than ideological ones in shaping the Declaration of Independence (Wood, 2019).

The Two-Part Test

Ask yourself two questions:

1. Would an educated reader in my field already know this? If yes, it may be common knowledge.
2. Can I find this exact claim in five or more general reference sources without attribution? If yes, it is almost certainly common knowledge.

If you answer "no" to either question, cite it. When in doubt, cite it. Over-citing is a minor stylistic issue; under-citing is an integrity issue.

Field-Specific Common Knowledge

What counts as common knowledge depends on your audience. In a biology paper, you do not need to cite the claim that DNA has a double-helix structure. In a history paper written for a general audience, you might. Always consider who your reader is.

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Signal Phrases and Integrating Citations Into Prose

Strong academic writing does not just drop parenthetical citations at the end of every sentence. Signal phrases - also called attributive tags - weave the source into your prose and give the reader context about the author's role.

Common Signal Phrase Verbs

Different verbs carry different implications. Choose carefully:

• Neutral: states, notes, observes, reports, points out, explains, describes
• Agreement/support: confirms, demonstrates, establishes, shows, verifies, supports
• Disagreement/critique: challenges, disputes, questions, refutes, rejects, criticizes
• Argumentation: argues, claims, contends, asserts, maintains, insists, proposes
• Suggestion/tentativeness: suggests, implies, indicates, hints, speculates

Examples in APA

According to Sweller (2019), cognitive load theory predicts a decline in performance under dual-task conditions.

Sweller (2019) demonstrated that performance declines under dual-task conditions, a finding that has since been replicated by Patel and Kim (2021).

As Torres et al. (2022) argued, early intervention "remains the single most effective strategy" (p. 89).

Examples in MLA

García argues that the narrator's unreliability "forces the reader into an active interpretive role" (87).

As Smith and Jones observe, the pattern is consistent across the author's later novels (112-115).

Examples in Chicago

Chen argues that architectural memory "is never purely visual."^1

As Park and Lin have shown, the relationship between urban design and community health is well established.^2

Varying Your Citations

Avoid the monotony of placing every citation in parentheses at the end of a sentence. Alternate between:

• Parenthetical citations at the end of a sentence.
• Narrative citations with signal phrases at the beginning or middle of a sentence.
• Integrated quotations where the author's name flows naturally into your sentence.

This variety makes your writing more readable and demonstrates your engagement with the sources.

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Common Mistakes and How to Avoid Them

Mistake 1: Missing Page Numbers for Direct Quotes

APA, MLA, Harvard, and Chicago all require a page number (or equivalent locator) when you quote directly. Omitting it is one of the most frequent citation errors.

Wrong (APA): "The effect was robust" (Sweller, 2019).

Correct (APA): "The effect was robust" (Sweller, 2019, p. 112).

Mistake 2: Using "Et Al." Too Early or Too Late

APA 7 and MLA 9 use "et al." from the first citation for works with three or more authors. Chicago notes do not use "et al." until there are four or more authors. Confusing these thresholds is common when switching between styles.

Mistake 3: Putting the Period in the Wrong Place

In APA, MLA, and Harvard, the period goes after the closing parenthesis of the citation, not before it.

Wrong: The results were significant. (Sweller, 2019)

Correct: The results were significant (Sweller, 2019).

The exception is block quotations, where the period goes before the parenthetical citation in both APA and MLA.

Mistake 4: Citing a Source You Did Not Read

If you found a reference in another author's work but did not read the original, you must use the secondary citation format ("as cited in" for APA, "qtd. in" for MLA). Listing a source in your reference list that you did not actually consult is academically dishonest.

Mistake 5: Inconsistent Formatting

Switching between styles in a single paper - using (Smith, 2019) in one paragraph and (Smith 45) in another - signals carelessness. Choose one style and apply it uniformly. The AllCitations style browser can help you identify which style your assignment requires.

Mistake 6: Forgetting to Include the Source in the Reference List

Every in-text citation must have a corresponding entry in your bibliography, reference list, or works cited page (and vice versa). The only exceptions are personal communications in APA and some note-only citations in Chicago.

Mistake 7: Citing Too Many Sources at Once

A parenthetical with six or more sources is hard to read and rarely necessary. If you are tempted to write (Adams, 2018; Brown, 2019; Clark, 2020; Davis, 2021; Evans, 2022; Foster, 2023), consider using a phrase like "Several studies have confirmed this finding (e.g., Adams, 2018; Clark, 2020; Foster, 2023)" or citing a review article instead.

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Specific Manual References

For readers who want to go deeper, here are the authoritative sources for each style:

• APA 7: Publication Manual of the American Psychological Association, 7th Edition (2020). Chapter 8 covers in-text citations; Chapter 9 covers reference list entries. The APA Style Blog publishes regular clarifications and examples.
• MLA 9: MLA Handbook, 9th Edition (2021). Chapter 5 covers in-text documentation. The MLA Style Center answers frequently asked questions.
• Chicago 17: The Chicago Manual of Style, 17th Edition (2017). Chapter 14 covers the notes-bibliography system; Chapter 15 covers the author-date system.
• Harvard: No single canonical manual. Check your university's library website for its specific Harvard guide.
• IEEE: IEEE Editorial Style Manual (updated periodically). Available through IEEE's author resources.
• Vancouver: Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals (ICMJE). Available at icmje.org.
• CSE: Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers, 8th Edition (2014).
• General reference: Purdue Online Writing Lab (OWL) - free, comprehensive guides for APA, MLA, and Chicago.

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Generate Your Citations Automatically

Formatting in-text citations by hand is tedious and error-prone. The AllCitations citation generator supports APA 7, MLA 9, and dozens of other styles. Paste a URL or DOI, select your style, and the tool produces both the reference list entry and the in-text citation. For a walkthrough on citing digital sources, see our guides on how to cite a website in APA 7 and how to cite a YouTube video.

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Frequently Asked Questions

What happens if I forget an in-text citation?

Failing to include an in-text citation for borrowed ideas, data, or quotations is a form of plagiarism, even if you list the source in your bibliography. The in-text citation is what connects the specific claim in your paper to its source. Without it, the reader has no way to know which ideas are yours and which belong to someone else. Most universities treat missing citations seriously, with consequences ranging from grade penalties to academic misconduct proceedings. If you are unsure whether something needs a citation, the safest approach is to include one.

Do I need a citation for common knowledge?

Common knowledge refers to facts that are widely known and easily verified by a general audience - for example, that the Earth orbits the Sun or that World War II ended in 1945. You do not need to cite common knowledge. However, the boundary depends on your discipline and audience. A fact that is common knowledge among biologists (e.g., the role of mitochondria in cellular respiration) may not be common knowledge in a first-year composition class. When in doubt, cite it. You will never be penalized for providing a citation, but you may face serious consequences for omitting one.

Can I use different citation styles in the same paper?

No. You must use one citation style consistently throughout a single document. Mixing styles - for example, using APA parenthetical citations in some paragraphs and MLA author-page citations in others - confuses the reader and is considered a formatting error. Your instructor, journal, or publisher will specify which style to use. If no style is specified, ask before you begin writing.

How do I cite the same source multiple times?

In author-date systems (APA, Harvard, CSE), simply repeat the same parenthetical citation each time: (Sweller, 2019). In author-page systems (MLA), repeat the parenthetical with the relevant page number: (Sweller 45), then later (Sweller 78). In numeric systems (IEEE, Vancouver), reuse the same number: [1] every time you cite that source. In notes-bibliography systems (Chicago), use the full note the first time and the shortened note for all subsequent citations.

What is the difference between a parenthetical citation and a narrative citation?

A parenthetical citation places all source information inside parentheses at the end of the sentence: "Cognitive load increases during task-switching (Sweller, 2019)." A narrative citation incorporates the author's name into the sentence itself, with only the remaining elements in parentheses: "Sweller (2019) found that cognitive load increases during task-switching." Both formats are equally valid. Narrative citations are useful when you want to emphasize the author or introduce a signal phrase. Parenthetical citations are better when the focus should remain on the information rather than the source.

How do I handle sources with no author, no date, or no page number?

Each style has specific rules for missing information. In APA, use the title in place of the author, "n.d." in place of the date, and paragraph numbers or section headings in place of page numbers. In MLA, use the title in place of the author and simply omit the page number if none is available. In numeric systems, the lack of an author does not affect the in-text citation at all since you are using a number. See the detailed examples for each style earlier in this guide.

Should I include page numbers for paraphrases?

It depends on the style. APA 7 encourages but does not require page numbers for paraphrases, especially for long or complex works. MLA strongly recommends including page numbers whenever they are available. Chicago notes generally include page numbers for both quotes and paraphrases. The best practice across all styles is to include a page number whenever you can, because it helps your reader locate the specific passage you are referencing.

Is there a difference between a bibliography, a reference list, and a works cited page?

Yes. A reference list (APA, CSE) includes only the sources you cited in your text. A works cited page (MLA) similarly includes only cited sources. A bibliography (Chicago notes-bibliography) may include sources you consulted but did not cite directly. The terminology matters because it signals which style you are using and what the reader should expect. Using the wrong heading - for example, titling your APA reference list "Bibliography" - is a formatting error.