AMA In-Text Citation: Superscript Numbers Done Right

TL;DR — AMA cites sources with superscript Arabic numerals, numbered in the order they first appear and reused for every later mention of the same source. The number sits outside periods and commas, inside colons and semicolons, after an author's name when one is given, and before a dash. Several sources in one place are listed as 1,4,7 or as a range 2-5. The reference list is numbered to match, not alphabetized.

AMA style, from the *AMA Manual of Style* (11th edition, 2020), is the citation system of medical, nursing, and many health-science programs. It is a numbered system: instead of author and year, the reader sees a small raised number and looks it up in the reference list. That makes the in-text side simpler than APA or MLA, and also less forgiving, because a single number out of sequence throws off the rest of the paper. The rules below govern where the number goes and how it behaves; if numbered citation is new to you, [Citations in Research Papers: A Practical Guide to Crediting Sources](/research-paper-citations-in-writing) explains what any citation system has to accomplish first. They are followed by a worked paragraph, the matching reference list, and the edge cases students meet in a typical assignment.

The core rules

1. Superscript Arabic numerals, nothing else. No parentheses around the number, no brackets, no author names or years in the citation itself. Word processors have a superscript button; use it rather than typing a caret.

2. Number in order of first appearance. The first source you cite is 1, the second is 2, and so on through the paper, including sources cited in tables, figure legends, and boxes at the point where the table or figure is first mentioned. The reference list follows the same order, so it is not alphabetical.

3. Reuse the number for every later citation of the same source. Source 3 is 3 on page 1 and still 3 on page 12. This is the rule students most often break by giving a repeated source a fresh number each time; the result is a reference list with duplicates.

4. Placement relative to punctuation. The number goes outside a period or comma, and inside a colon or semicolon. It follows a closing quotation mark or parenthesis.

...was confirmed in a second cohort.4
...was confirmed in a second cohort,4 although...
...three outcomes were tracked5: mortality, readmission, and length of stay.
...as the earlier trial suggested6; the mechanism remains unclear.
...described as "a modest but consistent effect."7

The one exception is a dash, which the number precedes: the two larger trials⁸—both unblinded—reported no difference.

5. Several sources at one point. Separate non-consecutive numbers with commas and no spaces: ^1,4,7. Show three or more consecutive numbers as a range with a hyphen: ^2-5. Combine the two when needed: ^1,3-6,9.

6. Authors named in the sentence. The number follows the name directly, not the end of the sentence: Marchetti et al³ reported… This tells the reader which source the name belongs to before they reach the claim.

7. Pages and other locators. To point at a specific page, add it in parentheses after the number, also in superscript: ^3(p112) for one page, ^3(pp112-115) for a range. This is used mainly for direct quotations and for long sources such as books and reports; journal articles rarely need it. The mechanics of trimming and integrating a quotation are the same as in any style (How to Use Quotes in an Essay Without Losing Your Own Voice), with the superscript replacing the parenthetical.

8. Sources that do not get a number. Personal communications (an email, an interview, a conversation) and unpublished data are not listed in the references. They are cited in the text in parentheses with the person’s name, the type of communication, and the date, and AMA expects you to have that person’s permission: (R. Anand, MD, email communication, March 2026).

A worked paragraph

The paragraph below is from an invented student review on hospital hand-hygiene programs. Every study and author in it is fictional; the citation mechanics are AMA. Read it once for sense, then again watching only the superscripts.

Hand-hygiene compliance on inpatient wards rarely exceeds 50% without a structured program.¹ Two multicenter trials reported that visible feedback on compliance rates raised adherence by 15 to 22 percentage points within 6 months,^2,3 and a smaller single-site study found a comparable gain when feedback was paired with unit-level rewards.⁴ Marchetti et al³ noted, however, that gains decayed once feedback stopped: compliance had returned to baseline by month 12 in three of the five hospitals they followed.^3(p1148) Reviews that pooled these results agree on the short-term effect but differ on how long it persists^1,5-7; the most recent of them concluded that “no trial to date has demonstrated durable change without ongoing measurement.”^7(p22) Whether that reflects the interventions or the limits of a 12-month follow-up remains unsettled.¹

What is happening, source by source:

Source 1 is cited three times (first sentence, mid-paragraph, final sentence) and keeps its number.
Sources 2 and 3 are cited together as ^2,3; source 3 then reappears alone after the authors’ name, and again with a page reference for a specific finding.
Sources 5, 6, and 7 are cited as a range, 5-7, joined to source 1 as ^1,5-7. The number sits before the semicolon.
The quotation from source 7 carries a page number in parentheses, and the number follows the closing quotation mark and the period.
Source 4 appears once. That is fine; a source cited once is still numbered in sequence.

The reference list that matches

Because the list is ordered by first citation, it is the mirror of the paragraph. AMA reference entries use author surnames with initials and no periods between initials, article titles in sentence case with no quotation marks, journal titles abbreviated as in the National Library of Medicine catalog and italicized, then year, volume, issue, and pages packed together with semicolons and colons.

References

1. Okonjo TA, Halvorsen M. Hand hygiene compliance in acute care: a systematic review. J Hosp Infect Pract. 2021;38(4):412-425. doi:10.0000/jhip.2021.38.4.412
2. Beaulieu R, Sandoval-Reyes I, Ng KW, et al. Real-time compliance feedback on medical wards: a cluster randomized trial. Infect Prev Q. 2022;15(2):88-101. doi:10.0000/ipq.2022.15.2.88
3. Marchetti L, Adeyemi F, Roth C. Sustained hand hygiene after feedback withdrawal: a five-hospital follow-up. Clin Ward Stud. 2023;27(6):1139-1152. doi:10.0000/cws.2023.27.6.1139
4. Petrova D, Lindgren S. Unit-level incentives and hand hygiene: a single-site study. Nurs Qual Rep. 2020;9(1):17-24.
5. Whitcombe AJ. Behavioral Approaches to Infection Control. 2nd ed. Ashford Medical Publishing; 2019.
6. Duarte-Ferreira P, Achebe N, Sung J, Kowalczyk M, Brennan T, Osei K. Durability of hygiene interventions: meta-analysis of 31 trials. J Hosp Infect Pract. 2022;39(2):201-219. doi:10.0000/jhip.2022.39.2.201
7. National Ward Safety Institute. Hand Hygiene Programs: Evidence Summary 2024. Published February 12, 2024. Accessed August 3, 2026. https://www.example.org/hygiene-summary-2024

Points to notice, because they carry over to your own list:

Author counts. List up to six authors in full (entry 6 has six). For seven or more, give the first three followed by et al (entry 2).
No publisher location for books in the 11th edition (entry 5); earlier editions included the city.
Journal abbreviations follow NLM conventions; look the title up in the NLM Catalog rather than inventing an abbreviation. Single-word journal titles are not abbreviated.
DOI is written as doi: followed by the identifier, with no period at the end.
Web sources carry a published or updated date and an accessed date, then the URL (entry 7). If the page has a named author, the author leads.
Page ranges keep all digits (1139-1152, not 1139-52) and use a hyphen.

The reference list is the half of the system that most style guides skip, and it is where errors surface. Matching every citation to exactly one entry is the whole discipline of the system.

Edge cases

Situation	What to do
Same source, different page, later in the paper	Same number, new page in parentheses: ^3(p1150)
Source first cited in a table	Number it by where the table is first mentioned in the text, not by where the table sits on the page
Two sentences in a row from one source, author named at the start	One number after the name covers the run; add it again if an intervening source breaks the sequence
Source cited only in a figure legend	Still numbered in sequence at the point the figure is first called out
Quotation longer than about four lines	Set as an indented block; the number follows the final punctuation, with a page reference
Citing a source you found inside another source	Cite the one you actually read; if you must cite the original, find and read it so the entry is accurate
Website with no date	Give the accessed date only
Software or dataset	Treat like a web source: name, version, publisher, year, URL, accessed date

Direct quotations in medical writing are rarer than in the humanities, and most AMA papers paraphrase. A paraphrase still needs its number; leaving it off because the words are yours is the route to accidental plagiarism, which How to Avoid Accidental Plagiarism in Your Essays covers.

How AMA differs from the systems you may know

Students arriving from APA or MLA courses carry habits that produce recognizable AMA errors.

No year in the text. (Marchetti et al, 2023) is APA. AMA puts only the number in the text and saves the year for the reference list.
No alphabetical reference list. Entry 1 is whichever source you cited first, even if the author’s surname starts with Z.
No “ibid.” Repeat the number.
No parentheses or brackets around the number. Bracketed numbers [3] belong to IEEE and Vancouver variants, not AMA.
Sentence case, no quotation marks for article titles in the list, and initials without periods (Okonjo TA, not Okonjo, T. A.).

For a side-by-side sense of how parenthetical systems handle the same job, MLA Page Format and In-Text Citations: A Practical Walkthrough is the closest comparison on this site.

Common mistakes

Renumbering a repeated source. Produces duplicate reference entries and a list longer than the number of sources.
Superscript before the period. “…second cohort⁴.” is wrong; the number follows the period.
Spaces or “and” between numbers. A citation written as 1, 4 and 7 should be ^1,4,7.
Ranges written out. ^2,3,4,5 should be ^2-5. Two consecutive numbers stay as a pair: ^2,3.
Numbers assigned in draft order, then paragraphs moved. After any restructuring, the first citation of some source is no longer first. Renumber at the end.
Personal communications in the reference list. They go in the text only, in parentheses.
Alphabetizing the reference list out of habit.
Inventing journal abbreviations. Check the NLM Catalog; an unrecognizable abbreviation is as unhelpful as no journal name.

Checklist

Every citation is a superscript Arabic numeral with no brackets or parentheses.
Numbers run 1, 2, 3… in order of first appearance, counting tables and figures at the point they are first mentioned.
Each source keeps one number for the whole paper.
Numbers sit outside periods and commas, inside colons and semicolons, after closing quotation marks, before dashes, and directly after an author’s name when one is given.
Multiple citations use commas with no spaces; three or more consecutive numbers become a hyphenated range.
Page references, where used, appear as n(pXX), raised as superscript.
Personal communications appear in the text in parentheses, not in the list.
The reference list is numbered to match, with up to six authors listed (first three plus et al for seven or more), NLM journal abbreviations, sentence-case titles, and DOIs where available.
Numbering was checked once more after the final edit.
Instructor’s or program’s local variations (period after et al, required accessed dates, page-range style) confirmed against the assignment guidelines.

Frequently asked questions

What happens to the numbering if I delete a citation while revising?

Every number after it shifts, in both the text and the reference list. This is the main reason to write the paper with placeholder markers (the author’s name in brackets, for instance) and assign numbers only when the draft is final. If you use citation software, set its output style to AMA and let it renumber automatically; if you number by hand, do it last and check the sequence once more after the final proofread.

How do I cite the same source twice in one paragraph in AMA style?

Use the same superscript number each time. AMA numbers sources, not citations, so source 4 is always 4 no matter how often it appears. Do not create a new entry in the reference list for the repeat, and do not use “ibid.” or “op. cit.”, which belong to other systems. If the second use points to a different page, add the page in parentheses after the number: 4(p112).

Can I put the citation number at the end of the paragraph to cover everything in it?

No. The number belongs to the sentence or clause that draws on the source, so a reader can tell which claim came from where. A paragraph built on one source may carry that source’s number after each sentence that uses it, which looks repetitive but is correct. When several sentences in a row summarize one study and the author is named at the start, one number after the name is enough for that stretch.

Does AMA style allow author names in the sentence at all?

Yes. Naming the author is a matter of emphasis, and the superscript number still follows the name, as in Marchetti et al followed by a raised 3. For one author use the surname; for two, both surnames joined by “and”; for three or more, the first surname and “et al” (AMA journals omit the period after “al”, though many instructors accept it). The year is never given in the text, only in the reference list.