Should the in-text citation be placed before or after the final punctuation mark

发表于 2023-12-13 Waline：

What is discussed in this question?

During the process of research writing, we often need to cite certain references. With the aid of reference management tools, we can efficiently modify the style of citations to meet the requirements of various publishers. However, I'm puzzled about whether the in-text citation should be positioned before or after the final punctuation mark.

Before we delve into this question, there are some definitions that need to be clarified. The process of citing references generally involves two parts—in-text citations and the bibliography.

The bibliography, also called reference lists, a list of all sources used in your research, is typically placed at the end of the text, as below^[1]:

References

Berezin, M. Y. & Achilefu, S. Fluorescence lifetime measurements and biological imaging. Chem. Rev. 110, 2641–2684 (2010).

Kandori, H., Katsuta, Y., Ito, M. & Sasabe, H. Femtosecond fluorescence study of the rhodopsin chromophore in solution. J. Am. Chem. Soc. 117, 2669–2670 (1995).

Baba, M., Li, Y. & Matsuoka, M. Intensity interference of ultrashort pulsed fluorescence. Phys. Rev. Lett. 76, 4697–4700 (1996).

Muskens,O. L., Giannini, V., Sánchez-Gil, J. A. & Rivas, J. G. ómez Strong enhancement of the radiative decay rate of emitters by single plasmonic nanoantennas. Nano Lett. 7, 2871–2875 (2007). ...

McGlynn, J. A., Wu, N. & Schultz, K. M. Multiple particle tracking microrheological characterization: fundamentals, emerging techniques and applications. J. Appl. Phys. 127, 201101 (2020).

Ghosh, A., Karedla, N., Thiele, JanChristoph, Gregor, I. & Enderlein, J. örg. Fluorescence lifetime correlation spectroscopy: Basics and applications. Methods 140–141, 32–39 (2018).

Newville, M., Stensitzki, T., Allen, D. B. & Ingargiola, A. LMFIT: nonlinear least-square minimization and curve-fitting for Python. https://doi.org/10.5281/zenodo.11813 (2023).

While an in-text citation is a marker links to a specific source within your text, which is inserted in text, such superscript numbers—"1", "2,3", "4,5", and "6" in the below text¹,

However, lifetimes can shorten down to 10's of femtoseconds depending on the nature of the fluorophore¹. As such, access to higher resolutions enables the use of femtosecond scale fluorophores^2,3, coupling to plasmonic devices which can increase quantum yield^4,5, and exploration of vibrational and rotational modes that act on the femtosecond scale⁶.

Or the "author-date" system enclose in parentheses in normal font—"(Bhatia, 2011, Blakeley and Jankovic, 2002)" in the below text²,

The paroxysmal dyskinesias (PD) are a heterogeneous group of episodic movement disorders that can be separated on the basis of factors that precede or precipitate attacks, the nature and durations of attacks, and etiology (Bhatia, 2011, Blakeley and Jankovic, 2002).

The first type of in-text citations is also referred to as note number or callout number in some style guides. Here, I refer to this type of in-text citation as superscript citation, which are those that are superscripted, to distinguish them from the second type of in-text citation.

The second type of in-text citation is usually enclosed in parentheses, neither superscripted nor subscripted, and appears in normal font. The parentheses may contain "author-date" or "number" information, and I refer to this type of citation as normal parenthetical citation.

The terms "superscript citation" and "normal parenthetical citation" are custom terms for discussing the placement of in-text citations, they are not used in any style guides.

After understanding the differences between those, let's return to the subject at hand: should the in-text citation be placed before or after the final punctuation mark? Which is the correct way to do it in the following sentences?

First sentence is from a article¹ published in the Nat. Commun., a journal by Nature Portfolio:

However, lifetimes can shorten down to 10's of femtoseconds depending on the nature of the fluorophore¹.

Second sentence is from another article³ published in the JACS, a journal by American Chemical Society:

Cancer-related illnesses are the second leading cause of death in the United States behind only heart disease.¹

We can find two different methods in the text above. In the first example, the in-text citation marker—"1" is placed before the period, while in the second example, the "1" is placed after the period. More, you can even find that articles published by Nature Portfolio almost all use the first citation style, while articles published by ACS almost all use the second method.

So, which is the correct method for placing in-text citations, or are both methods correct?

What is stated in the style guide?

I will list the descriptions of several popular style guides regarding the position of in-text citations below.

APA Style

APA (American Psychological Association) style is most commonly used to cite sources within the social sciences. This resource, revised according to the 7th edition of the APA manual, offers examples for the general format of APA research papers, in-text citations, endnotes/footnotes, and the reference page.⁴

Superscript citation

2.13 Footnotes

Footnote Callout Numbering and Format. Number all footnotes consecutively in the order in which their callouts appear in the text with superscript Arabic numerals. Footnote callouts should be superscripted, likethis,¹ following any punctuation mark except a dash. A footnote callout that appears with a dash—like this²—always precedes the dash. (The callout falls inside a closing parenthesis if it applies only to matter within the parentheses, like this.³) Do not put a space before the footnote callout in text. Do not placefootnote callouts in headings. To refer to a footnote again after it has been called out, identify it in the text by the footnote number (e.g., write "see Footnote 3"); do not repeat the footnote callout or the whole footnote. ...

From Publication Manual of the American Psychological Association, 7th edition (2019).

Normal parenthetical citation

8.11 Parenthetical and Narrative Citations

In-text citations have two formats: parenthetical and narrative. In parenthetical citations, the author name and publication date (or equivalent information; see Section 9.12) appear in parentheses. In narrative citations, this information is incorporated into the text as part of the sentence.

Parenthetical Citation. Both the author and the date, separated by a comma, appear in parentheses for a parenthetical citation. A parenthetical citation can appear within or at the end of a sentence. When a parenthetical citation is at the end of a sentence, put the period or other end punctuation after the closing parenthesis.

Falsely balanced news coverage can distort the public's perception of expert consensus on an issue (Koehler, 2016). ... Narrative Citation. The author appears in running text and the date appears in parentheses immediately after the author name for a narrative citation.

Koehler (2016) noted the dangers of falsely balanced news coverage.

From Publication Manual of the American Psychological Association, 7th edition (2019).

MLA Style

MLA (Modern Language Association) style is most commonly used to cite sources within the language arts, cultural studies, and other humanities disciplines.⁴

Superscript citation

7.4 Placement of Notes in the Text

Note numbers in the text are generally placed after a mark of punctuation. Whenever possible, place them at the end of sentences.

Critics are divided on whether the interplay of genres is successful in the film.¹

An exception is the dash, which is placed after, not before, a note number.

Positioned in the margins of each scene, the servant⁴—immobilized, silent, cast in shadow—uncannily substantiates Rodriguez's claim.

If clarity demands that the note be placed somewhere other than at the end of the sentence or if the sentence requires more than one note, find the least distracting unambiguous spot.

Placement of note mid-sentence, for clarity of citations

Despite Fredric Jameson's influential imperative to historicize,⁵ Chakrabarty has criticized the "continuous, homogenous" characteristics of this understanding of history (111).

Placement of more than one note in a sentence

Huck's reverence for the circus—like his admiration for the Shakespeare rehearsal (which hesays "knocked the spots out of any acting ever I see before" [Twain 125]⁶)—is so intense that it ultimately parodies itself.⁷

From MLA Handbook, 9th edition (2021).

Normal parenthetical citation

Citing Sources in the Text

[6.1] In-Text Citations

In-text citations are brief, unobtrusive references that direct readers to the works-cited-list entries for the sources you consulted and, where relevant, to the location in the source being cited.

[6.2] Overview

An in-text citation begins with the shortest piece of information that directs your reader to the entry in the works-cited list. Thus, it begins with whatever comes first in the entry: the author's name or the title (or description) of the work. The citation can appear in your prose or in parentheses.

Citation in prose > Naomi Baron broke new ground on the subject.

Parenthetical citation > At least one researcher has broken new ground on the subject (Baron).

Work cited > Baron, Naomi S. "Redefining Reading: The Impact of Digital Communication Media."PMLA, vol. 128, no. 1, Jan. 2013, pp. 193–200. ...

From MLA Handbook, 9th edition (2021).

The Chicago Manual of Style

The Chicago Manual of Style (CMOS) is most commonly used by those working in literature, history, and the arts.⁴

Superscript citation

14.26 Placement of note number.

A note number should generally be placed at the end of a sentence or at the end of a clause. The number normally follows a quotatioa (whether it is run in to the text or set as an extract) . Relative to other punctuation, the number follows any punctuation mark except for the dash, which it precedes.

"This," wrote George Templeton Strong, "is what our tailors can do."¹

It was the hour of "national paths" toward socialism;⁹ but that expression, which turned out to be temporary, was more an incantation than a discovery.

The bias was apparent in the Shotwell series³—and it must be remembered that Shotwell was a student of Robinson's.

A note number should generally be placed at the end of a sentence or at the end of a clause. The number normally follows a quotation (whether it is run in to the text or set as an extract). Relative to other punctuation, the number follows any punctuation except for the dash, which it precedes.

(In an earlier book he had said quite the opposite.)²

Men and their unions, as they entered industrial work, negotiated two things: young women would be laid off once they married (the commonly acknowledged "marriage bar"¹), and men would be paid a "family wage."

From Chicago Manual of Style, 17th edition (2017).

Normal parenthetical citation

Attributing Quotations in Text

13.64 Use of parentheses with in-text citations. If the source of a direct quotation is not given in a note, it is usually placed in the text in parentheses. Although the source normally follows a quotation, it may come earlier if it fitsmore smoothly into the introductory text (as in the second example in 13.65) . The examples in this section focus on full and short forms of parenthetical citation that may be needed in shorter works with no notes or bibliography or to provide in-text citations to a frequently quoted work. The advice in this section on placement relative to surrounding text is intended to supplement the system of notes and bibliography covered in chapter 14. For author-date references, see chapter 15.

13.65 Full in-text citation. An entire source may be given in parentheses immediately following a quotation (as in the first example below), or some of the data may be worked into the text (as in the second example) , with details confined to parentheses. See also 6.101. For more on the proper form for full citations, see 14.23.

"If an astronaut falls into a black hole, its mass will increase, but eventually the energy equivalent of that extra mass will be returned to the universe in the form of radiation. Thus, in a sense, the astronaut will be 'recycled' " (Stephen W. Hawking, A Brief History of Time: From the Big Bang to Black Holes [New York: Bantam Books, 1988] , 112).

In their introduction to Democracy in America (University of Chicago Press, 1999) , translators Harvey Mansfield and Delba Winthrop write that Tocqueville "shows that the people are sovereign, whether through the Constitution or despite it, and he warns of the tyranny of the majority" (xvii) .

From Chicago Manual of Style, 17th edition (2017).

Oxford Style

The New Oxford Style, based on New Hart’s Rules, is a comprehensive guide to preparing copy for publication in print and electronically.

Superscript citation

17.2.3 Numbering and placement

The reader is referred to a footnote or endnote by a cue in the text. This normally takes the form of a superior Arabic number. The cue is placed after any punctuation (normally after the closing point of a sentence). If, however, it relates only to text within parentheses it is placed before the closing parenthesis. The cue is repeated at the start of the note. Notes cued in the middle of a sentence are a distraction to the reader, and cues are best located at the end of sentences:

He was a genuine Shropshire lad, as John H. Johnston reminds us.¹

Bergonzi quite correctly notes, 'Owen's attitude to the "boys" or "lads" destined for sacrifice has some affinity with Housman's.'⁵⁵

(Hopkins wrote defensively to Bridges: 'When you read it let me know if there is anything like it in Walt Whitman; as perhaps there may be, and I should be sorry for that.'²⁹)

Characters other than Arabic numerals may be used for note cues when there are relatively few notes in a sequence. In mathematical or scientific contexts, for example, superior lower-case letters may be used to avoid confusion with superscript numbers in technical notation. Lower-case Roman numerals may also serve as note cues, as can reference marks (the traditional order is *, †, ‡, §, ¶, ||, repeated in duplicate as **, ††, and so on as necessary). Occasionally different types of cue are employed on the same page for parallel sequences of notes serving different purposes. ...

From New Oxford Style Manual, 2nd edition (2012).

Normal parenthetical citation

17.3.2 References in text

A typical reference in the text consists of an author's name and date of publication enclosed within parentheses (or occasionally square brackets), with or without a comma separating name and date, according to the style adopted. The reference is placed immediately after the statement to which it relates. If this happens to be at the end of a sentence the closing parenthesis precedes the closing point (but a reference at the end of a displayed quotation follows the closing punctuation). If the author's name is given in open text it need not be repeated in the parentheses, where the date alone suffices. Several references may be included within the same parentheses, separated by semicolons:

text > While there was an extraordinary sense of optimism among people establishing their own farms in the early years of independence (Unwin 1994), this is rapidly withering away. reference section > Unwin, T. (1994), 'Structural Change in Estonian Agriculture: From Command Economy to Privatisation', Geography, 79, 3: 246-61. text > For years, most textbooks referred to the five stages of economic integration as defined by Balassa (1961). reference section > Balassa, Bela (1961), The Theory of Economic Integration. London: Allen and Unwin. text > They are also used to detect segmental hypermobility (Magarey 1988; Maitland 2001). reference section > Magarey, M. E. 1988 'Examination of the Cervical and Thoracic Spine'. In: R. Grant (ed.) Physical Therapy of the Cervical and Thoracic Spine, pp. 81-109. Churchill Livingstone: New York. > Maitland, G. 2001 Maitland's Vertebral Manipulation, 6th edn. Butterworth-Heinemann: Oxford. ...

From New Oxford Style Manual, 2nd edition (2012).

IEEE Style

The Institute of Electrical and Electronics Engineers (IEEE) style is a style widely used among all branches of engineering, computer science, and other technological fields.⁴

Superscript citation

C. Other Text ... Footnotes ... The footnote numbers are superscripts in text and in the actual footnotes. In text, place the superscript footnote numbers after punctuation such as periods, commas, parentheses, and quotation marks, but generally before dashes, colons, and semicolons in a compound sentence. ...

From IEEE Editorial Style Manual for Authors (Updated 28 November 2023).

Normal parenthetical citation

A. References in Text

References need not be cited in the text. When they are, they appear on the line, in square brackets, inside the punctuation. Grammatically, they may be treated as if they were footnote numbers, e.g.:

as shown by Brown [4], [5]; as mentioned earlier [2], [4]–[7], [9]; Smith [4] and Brown and Jones [5]; Wood et al. [7]

NOTE: Use et al. when three or more names are given for a reference cited in the text.

or as nouns:

as demonstrated in [3]; according to [4] and [6]–[9].

In-text references to text sections are written: "in Section II" or "in Section II-A" or "in Section II-A1." Capitalize the word "Section." Do not use the word "Subsection"; use "Section" and write out the complete citation. Note that there is no period in Section II-A1 to separate the subsections.

From IEEE Reference Guide (V 11.29.2023).

ACS Style

ACS Style refers to the citation format of the American Chemical Society which includes over more than 50 journals.

Citing References in Text

In ACS publications, you may cite references in text in three ways:

By superscript numbers, which appear outside the punctuation if the citation applies to a whole sentence or clause.

Oscillation in the reaction of benzaldehyde with oxygen was reported previously.³

By italic numbers in parentheses on the line of text and inside the punctuation.

The mineralization of TCE by a pure culture of a methane-oxidizing organism has been reported (6).

By author name and year of publication in parentheses inside the punctuation (known as author–date).

The primary structure of this enzyme has also been determined (Finnegan et al., 2004).

In ACS books, all three of these systems are used, depending on the subject matter and series. ...

From The ACS Style Guide, 3rd edition (2006).

RSC Style

The Royal Society of Chemistry has a specific referencing style that is used across all of its journals.

Referencing in the text

Use superscript numbers to show when a statement in your text has an external reference source, for example Wittig.³ Usually these should appear at the end of the sentence (after the punctuation), but can be after the relevant word or compound. ... The author(s) can be mentioned at their first citation in the text, but initials are not necessary. For papers with one or two authors simply state the name(s), and for papers with three or more authors you should use the first name followed by et al. Et al. is a Latin abbreviation for 'and other persons'.

Smith and Jones used this method for the first time.²

Plata et al. used HPLC to determine the carbohydrates present during a Saccharomyces fermentation.⁷ ...

From How to reference using the Royal Society of Chemistry style (Recorded on December 7, 2023).

Discussion and Conclusions

"Ethics, copyright laws, and courtesy to readers require authors to identify the sources of direct quotations and of any facts of opinions not generally known or easily checked."

From Chicago Manual of Style, 17th edition (2017).

In my opinion, in-text citations should be placed as close as possible to the content being cited.

When we directly quote the original text and enclose it in quotation marks, the in-text citation should immediately follow the closing quotation mark. The above style guide also follows this convention. For certain special words or phrases that are not enclosed in quotation marks, the in-text citation will also immediately follow these words or phrases.

Inactivating mutations in genes encoding for lysosomal hydrolases and transporters result in a spectrum of catabolic diseases known as lysosomal storage disorders^17,22 with a combined incidence of at least 1:5,000 live births.²³

From Cell⁵.

When summarizing and citing other people’s opinions, we often need to annotate the entire sentence. The position of superscript citation and normal parenthetical citation will be different.

The superscript citations should be placed after punctuation such as periods, commas, parentheses, and quotation marks, but generally before dashes, colons, and semicolons in a compound sentence.

We can think of superscript citation as a punctuation-like number, so it needs to be immediately followed by the punctuation without any space in between. A space is needed between the punctuation and the next sentence. For example, in the following text: "heart disease.¹ Pancreatic cancer":

Cancer-related illnesses are the second leading cause of death in the United States behind only heart disease.¹ Pancreatic cancer is the third leading cause of cancer death and is projected to be the second deadliest cancer by 2040, exemplified by a dismal 12% five year survival rate for patients with the disease.^2,3

From JACS³.

Note: Some journal publishers, such as Nature Portfolio, place superscript citations before punctuation. I think this is more of a proprietary convention. Unless you are submitting to their journal, I do not recommend writing in this way.

And normal parenthetical citation is usually placed before punctuation, such as:

We visualized and compared the CNV results from CGI with the Integrated Genome Viewer (Robinson et al., 2011). We converted the junction data to SVs with cgatools and then visualized and compared them with custom scripts and Circos.

From Cell Reports².

Although it may seem a bit strange, many style guides do indeed specify this convention.

Here’s my guess: we can think of superscript citations as punctuation-like numbers. They are formatted differently from the preceding text, so readers can easily recognize them as in-text citations. Therefore, they can be placed immediately after the punctuation without any space. Furthermore, we can understand that this in-text citation is a comment on the previous sentence.

However, when using normal parenthetical citation, since the in-text citation is formatted the same as the preceding text, if we place the normal parenthetical citation after the punctuation, it may cause confusion: “(Robinson et al., 2011)” Is it an independent sentence, or is it a comment on the previous or next sentence?

We visualized and compared the CNV results from CGI with the Integrated Genome Viewer. (Robinson et al., 2011) We converted the junction data to SVs with cgatools and then visualized and compared them with custom scripts and Circos.

Unless the journal has specific requirements, it is recommended to refer to the following table:

	Direct Citation	Indirect Citation
Superscript citation	following the content being cited	at the end of sentences after punctuation
Normal parenthetical citation	following the content being cited	at the end of sentences before punctuation

Appendix

Note: For Simplified Chinese Writer.

中文引注规范中少有提及引注符号的位置，我只在 2019 年出版的《法学引注手册》找到相关描述：

引注符号的位置

对全句的引用，引注符号置于句号、问号等标点之后。对句子部分内容的引用，引注符号置于该部分之后；对句中字词的直接引用，引注符号应当紧接引号，置于其他标点之前。例如：

在《行政诉讼法》起草过程中，关于受案范围问题曾有热烈的讨论。¹尽管多数学者主张概括规定法院应当受理的案件范围，以使受案范围尽量宽泛，²立法最终采取了逐项列举的方式。比起此前各个单行法，《行政诉讼法》规定的受案范围“有所扩大”³，但与概括规定的主张还相距很远。

观点与上述各英文 Style guide 基本一致。