How are citations numbered in an IEEE paper?

Citations are numbered in square brackets according to the exact order they appear in the manuscript text, beginning with [1]. If reference [1] is cited again later in Chapter 4, it retains the number [1] throughout the entire paper.

How do you cite multiple sources together in IEEE style?

Separate non-consecutive numbers with commas and enclose each in brackets: '[1], [3], [5]'. For consecutive ranges of three or more sources, use an en dash: '[1]–[3]'. Never combine them into a single bracket like '[1-3]' or '[1, 3]' in standard IEEE publishing.

Does the IEEE reference list follow alphabetical order?

No. Unlike APA or MLA which sort alphabetically by author surname, the IEEE Reference List is strictly sorted in numerical order matching the chronological appearance in the body text ([1], [2], [3], etc.).

Engineering & CS Standards

IEEE Citation Format Guide: Numbered Bracket Rules, In-Text Ordering & Common Pitfalls

Updated: November 14, 2026 • 6 min read • IEEE Transactions Standard

Core Rule: Square Brackets, Sequential Numbering & Grammatical Integration

IEEE citation style uses numbered square brackets on the baseline (e.g., [1]), never superscripts ¹ and never author-year parentheses (Smith, 2021).

Chronological assignment: Reference numbers are assigned in order of appearance in text. The first cited work is always [1].
Multiple citations: Use separate brackets with commas for discrete items ([1], [3], [7]) or an en dash for ranges ([2]–[5]).
Treat the bracket as a noun: Write "as demonstrated in [4]", NOT "as demonstrated in ref. [4]" or "as demonstrated in (4)".

The Reference List at the end is strictly numerical (1, 2, 3...), never alphabetical.

In-Text Citation Syntax Patterns

In IEEE manuscripts, in-text citations serve as grammatical components of the sentence. Adhere to these exact punctuation and spacing conventions:

Citation Scenario	Correct IEEE Syntax	Incorrect (Disallowed)
Single source	`...as shown by Miller [1].`	...as shown by Miller (2020) [1]
Grammatical subject	`[3] proposed a novel convolution filter.`	Ref. [3] proposed... / Author [3] proposed...
Multiple discrete sources	`...previous studies [2], [5], [9] confirm...`	...previous studies [2, 5, 9] confirm...
Continuous range (≥ 3)	`...recent benchmarks [4]–[7] indicate...`	...benchmarks [4-7] indicate...
Specific page or section	`[6, p. 124] or [6, Sec. II-B]`	[6]: 124 or [6] (p. 124)

Punctuation Placement Rules

Punctuation placement around IEEE bracket citations is rigid and often trips up authors transitioning from APA or MLA:

Inside vs. Outside Punctuation: The bracket goes before the period or comma: ...as confirmed in recent telemetry [12]. (Period is outside the bracket).
Space Before Brackets: Always place an ordinary space between the preceding word and the opening bracket: algorithm [5], never algorithm[5].
Sentence Beginnings: When opening a sentence with a reference number, write "Reference [8] provides an analysis..." to prevent a bare bracket starting the line, or rephrase to place the bracket internally.

Reference List Architecture (Top 3 Media Types)

The IEEE reference list must follow strict abbreviations (e.g., IEEE Trans. Electron Devices) and author initials preceding surnames.

1. Journal Article

Format: [#] J. K. Author, "Name of paper," Abbrev. Title of Periodical, vol. x, no. x, pp. xxx–xxx, Month, Year, doi: 10.1109/xxx.

[1] H. Zhang and C. Liu, "Deep residual networks for high-frequency trading," IEEE Trans. Neural Netw. Learn. Syst., vol. 34, no. 5, pp. 2410–2422, May 2023, doi: 10.1109/TNNLS.2021.3129481.

2. Conference Proceedings Paper

Format: [#] J. K. Author, "Title of paper," in Abbreviated Name of Conf., City of Conf., Abbrev. State (if applicable), Country, Year, pp. xxx–xxx.

[2] S. Vaswani et al., "Attention is all you need," in Proc. 31st Int. Conf. Neural Inf. Process. Syst. (NeurIPS), Long Beach, CA, USA, 2017, pp. 6000–6010.

3. Book

Format: [#] J. K. Author, Title of Book, xth ed. City of Publisher, State, Country: Abbrev. of Publisher, Year.

[3] I. Goodfellow, Y. Bengio, and A. Courville, Deep Learning. Cambridge, MA, USA: MIT Press, 2016.

The Fatal Sequence Trap in Thesis Revision

In large engineering theses, authors frequently rearrange paragraphs during late editing. If you move a paragraph containing reference [14] to the introduction before reference [2], your entire sequence breaks.

The Out-of-Sequence Rejection Hazard

IEEE conference and journal submission portals (IEEE Xplore, ScholarOne) employ automated format validators. If the validator detects that reference [5] appears in text before reference [4], the manuscript is automatically returned to the author without entering peer review.

Always run a sequential consistency check on your PDF draft to guarantee that numbers strictly ascend without skipping or retrograde ordering.

Audit IEEE Numbered Bracket Sequences Automatically

Paste your draft into CitePure. Our draft parser validates bracket sequences ([1], [2], [3]...), flags out-of-order markers, and verifies that every corresponding journal article exists in Crossref.

Check IEEE Sequences Now →

Frequently Asked Questions

When should I use "et al." in IEEE style?

In text, if a work has three or more authors, you may write "Miller et al. [1]". In the reference list, IEEE specifies that if there are up to six authors, list all of them. If there are seven or more authors, list the first author followed by "et al."

Can I use superscript numbers like in Nature or Science?

No. Nature and AMA style use superscripts (¹), but IEEE strictly mandates on-the-line square brackets ([1]).

How do I cite online preprints (arXiv) in IEEE style?

List author, title, "arXiv preprint arXiv:XXXX.XXXXX", and publication year: [7] A. Author, "Title of preprint," arXiv:2301.01234, 2023.