Thedash is apunctuation mark consisting of a long horizontal line. It is similar in appearance to thehyphen but is longer and sometimes higher from thebaseline. The most common versions are theendash–, generally longer than the hyphen but shorter than theminus sign; theemdash—, longer than either the en dash or the minus sign; and thehorizontalbar―, whose length varies acrosstypefaces but tends to be between those of theen andem dashes.[a]
Typical uses of dashes are to mark a break in a sentence, to set off an explanatory remark (similar to parenthesis), or to show spans of time or ranges of values.
The em dash is sometimes used as a leading character to identify the source of a quoted text.
In the early 17th century, inOkes-printedplays ofWilliam Shakespeare, dashes are attested that indicate a thinking pause, interruption, mid-speech realization, or change of subject.[1] The dashes are variously longer⸺ (as inKing Lear reprinted 1619) or composed of hyphens--- (as inOthello printed 1622); moreover, the dashes are often, but not always, prefixed by a comma, colon, or semicolon.[2][3][1][4]
In 1733, inJonathan Swift'sOn Poetry, the termsbreak anddash are attested for⸺ and— marks:[5]
Blot out, correct, insert, refine, Enlarge, diminish, interline; Be mindful, when Invention fails; To scratch your Head, and bite your Nails.
Your poem finish'd, next your Care Is needful, to transcribe it fair. In modern Wit all printed Trash, is Set off with num'rousBreaks⸺andDashes—
Usage varies both within English and within other languages, but the usual conventions for the most common dashes in printed English text are these:
An (unspaced) em dash or aspaced en dash can be used to mark a break in a sentence, and a pair can be used to set off aparenthetical phrase. For example:
Glitter, felt, yarn, and buttons—his kitchen looked as if a clown had exploded. A flock of sparrows—some of them juveniles—alighted and sang.
Glitter, felt, yarn, and buttons – his kitchen looked as if a clown had exploded. A flock of sparrows – some of them juveniles – alighted and sang.
An en dash, but not an em dash, indicates spans or differentiation, where it may replace "and", "to", or "through".[6] For example:
The French and Indian War (1754–1763) was fought in western Pennsylvania and along the present US–Canada border
— Edwards, pp. 81–101.
An em dash or horizontal bar, but not an en dash, is used to set off the source of a directquotation. For example:
Seven social sins: politics without principles, wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, and worship without sacrifice.
A horizontal bar (also calledquotation dash)[7] or the em dash, but not the en dash, introduces quoted text.
In informal contexts, ahyphen-minus (-) is often used as a substitute for an endash, as is a pair of hyphen-minuses (--) for an emdash, because the hyphen-minus symbol is readily available on most keyboards.[8] Theautocorrection facility of word-processing software often corrects these to the typographically correct form of dash.
Thefigure dash‒ (U+2012‒FIGURE DASH) has the same width as a numerical digit. (Manycomputer fonts have digits of equal width.[9]) It is used within numbers, such as the phone number 555‒0199, especially in columns so as to maintain alignment. In contrast, the en dash– (U+2013–EN DASH) is generally used for a range of values.[10]
Theminus sign− (U+2212−MINUS SIGN)glyph is generally set a little higher, so as to be level with the horizontal bar of theplus sign. In informal usage, thehyphen-minus- (U+002D-HYPHEN-MINUS), provided as standard on most keyboards, is often used instead of the figure dash.
InTeX, the standard fonts have no figure dash; however, the digits normally all have the same width as the en dash, so an en dash can be a substitution for the figure dash. InXeLaTeX, one can use\char"2012.[11] TheLinux Libertine font also has the figure dash glyph.
Theen dash,en rule, ornut dash[12]– is traditionally half the width of anem dash.[13][14]In modern fonts, the length of the en dash is not standardized, and the en dash is often more than half the width of the em dash.[15] The widths of en and em dashes have also been specified as being equal to those of the uppercase letters N and M, respectively,[16][17]and at other times to the widths of the lower-case letters.[15][18]
The en dash is commonly used to indicate a closed range of values – a range with clearly defined and finite upper and lower boundaries – roughly signifying what might otherwise be communicated by the word "through" in American English, or "to" in International English.[19] This may include ranges such as those between dates, times, or numbers.[20][21][22][23] Variousstyle guides restrict this range indication style to only parenthetical or tabular matter, requiring "to" or "through" in running text. Preference for hyphen vs. en dash in ranges varies. For example, theAPA style (named after the American Psychological Association) uses an en dash in ranges, but theAMA style (named after the American Medical Association) uses a hyphen:
President Jimmy Carter, in office from 1977 to 1981
Some style guides (including theGuide for the Use of the International System of Units (SI) and theAMA Manual of Style) recommend that, when a number range might be misconstrued as subtraction, the word "to" should be used instead of an en dash. For example, "a voltage of 50 V to 100 V" is preferable to using "a voltage of 50–100 V". Relatedly, in ranges that include negative numbers, "to" is used to avoid ambiguity or awkwardness (for example, "temperatures ranged from −18°C to −34°C"). It is also considered poor style (best avoided) to use the en dash in place of the words "to" or "and" in phrases that follow the formsfrom X to Y andbetween X and Y.[21][22]
The en dash is used to contrast values or illustrate a relationship between two things.[20][23] Examples of this usage include:
Australia beat American Samoa 31–0.
Radical–Unionist coalition
Boston–Hartford route
New York–London flight (however, it may be argued thatNew York–to-London flight is more appropriate because New York is a single name composed of two valid words; with a single en dash, the phrase is ambiguous and could mean eitherFlight from New York to London orNew flight from York to London; such ambiguity is assuaged when used mid-sentence, though, because of the capital N in "New" indicating it is a special noun). If dash–hyphen use becomes too unwieldy or difficult to understand, the sentence can be rephrased for clarity and readability; for example, "The flight from New York to London was a pleasant experience".[23]
A distinction is often made between "simple" attributive compounds (written with a hyphen) and other subtypes (written with an en dash); at least one authority considers name pairs, where the paired elements carry equal weight, as in theTaft–Hartley Act to be "simple",[21] while others consider an en dash appropriate in instances such as these[24][25][26] to represent the parallel relationship, as in theMcCain–Feingold bill orBose–Einstein statistics. When an act of the U.S. Congress is named using the surnames of the senator and representative who sponsored it, the hyphen-minus is used in theshort title; thus, the short title ofPublic Law 111–203 is "The Dodd-Frank Wall Street Reform and Consumer Protection Act", with ahyphen-minus rather than an en dash between "Dodd" and "Frank".[27] However, there is a difference between something named for a parallel/coordinate relationship between two people – for example,Satyendra Nath Bose andAlbert Einstein – and something named for a single person who had acompound surname, which may be written with a hyphen or a space but not an en dash – for example, theLennard-Jones potential [hyphen] is named after one person (John Lennard-Jones), as areBence Jones proteins andHughlings Jackson syndrome. Copyeditors use dictionaries (general, medical, biographical, and geographical) to confirm theeponymity (and thus the styling) for specific terms, given that no one can know them all offhand.
In English, the en dash is usually used instead of ahyphen incompound (phrasal) attributives in which one or both elements is itself a compound, especially when the compound element is anopen compound, meaning it is not itself hyphenated. This manner of usage may include such examples as:[21][22][28][29]
The hospital–nursing home connection (the connection between thehospital and thenursing home, not ahome connection between thehospital andnursing)
A nursing home–home care policy (a policy about thenursing home andhome care)
(Comparepost-war era, which, if not fully compounded (postwar), takes a hyphen, not an en dash. The difference is thatwar is not an open compound, whereasWorld War II is.)
The disambiguating value of the en dash in these patterns was illustrated by Strunk and White inThe Elements of Style with the following example: WhenChattanooga News andChattanooga Free Press merged, the joint company was inaptly namedChattanooga News-Free Press (using a hyphen), which could be interpreted as meaning that their newspapers were news-free.[30]
An exception to the use of en dashes is usually made whenprefixing an already-hyphenated compound; an en dash is generally avoided as a distraction in this case. Examples of this include:[30]
An en dash can be retained to avoid ambiguity, but whether any ambiguity is plausible is a judgment call.AMA style retains the en dashes in the following examples:[31]
As discussed above, the en dash is sometimes recommended instead of a hyphen incompound adjectives where neither part of the adjective modifies the other—that is, when each modifies the noun, as inlove–hate relationship.
First, use it to indicate ranges of time, money, or other amounts, or in certain other cases where it replaces the word "to".
Second, use it in place of a hyphen in a compound adjective when one of the elements of the adjective is an open compound, or when two or more of its elements are compounds, open or hyphenated.[32]
That is, theCMOS favors hyphens in instances where some other guides suggest en dashes, with the 16th edition explaining that "Chicago's sense of the en dash does not extend tobetween", to rule out its use in "US–Canadian relations".[33]
In these two uses, en dashes normally do not have spaces around them. Some make an exception when they believe avoiding spaces may cause confusion or look odd. For example, compare"12 June – 3 July" with"12 June–3 July".[34] However, other authorities disagree and state there should be no space between an en dash and adjacent text. These authorities would not use a space in, for example,"11:00 a.m.–1:00 p.m."[35] or"July 9–August 17".[36][37]
En dashes can be used instead of pairs of commas that mark off a nested clause or phrase. They can also be used around parenthetical expressions – such as this one – rather than the em dashes preferred by some publishers.[38][8]
The en dash can also signify a rhetorical pause. For example, anopinion piece fromThe Guardian is entitled:
Who is to blame for the sweltering weather? My kids say it's boomers – and me[39]
In these situations, en dashes must have a single space on each side.[8]
In most uses of en dashes, such as when used in indicating ranges, they are typeset closed up to the adjacent words or numbers. Examples include "the 1914–18war" or "the Dover–Calais crossing". It is only when en dashes are used in setting off parenthetical expressions – such as this one – that they take spaces around them.[40] For more on the choice of em versus en in this context, seeEn dash versus em dash.
When an en dash is unavailable in a particularcharacter encoding environment—as in theASCII character set—there are some conventional substitutions. Often two consecutive hyphens are the substitute.
The en dash is encoded in Unicode as U+2013 (decimal 8211) and represented in HTML by thenamed character entity–.
The en dash is sometimes used as a substitute for theminus sign, when the minus sign character is not available since the en dash is usually the same width as a plus sign and is often available when the minus sign is not; seebelow. For example, the original 8-bitMacintosh Character Set had an en dash, useful for the minus sign, years before Unicode with a dedicated minus sign was available. The hyphen-minus is usually too narrow to make a typographically acceptable minus sign. However, the en dash cannot be used for a minus sign inprogramming languages because the syntax usually requires a hyphen-minus.
Theem dash,em rule, ormutton dash[12]— is longer than anen dash. The character is called anem dash because it is oneem wide, a length that varies depending on the font size. One em is the same length as the font's height (which is typically measured inpoints). So in 9-point type, an em dash is nine points wide, while in 24-point type the em dash is 24 points wide. By comparison, the en dash, with its1en width, is in mostfonts either a half-em wide[41]or the width of an upper-case "N".[42]
The em dash is encoded in Unicode as U+2014 (decimal 8212) and represented in HTML by the named character entity—.
The em dash is used in several ways. It is primarily used in places where a set ofparentheses or acolon might otherwise be used,[43][full citation needed] and it can also show an abrupt change in thought (or an interruption in speech) or be used where afull stop (period) is too strong and acomma is too weak (similar to that of a semicolon). Em dashes are also used to set off summaries or definitions.[44] Common uses and definitions are cited below with examples.
It may indicate an interpolation stronger than that demarcated by parentheses, as in the following fromNicholson Baker'sThe Mezzanine (the degree of difference is subjective).
"At that age I once stabbed my best friend, Fred, with a pair of pinking shears in the base of the neck, enraged because he had been given the comprehensive sixty-four-crayon Crayola box—including the gold and silver crayons—and would not let me look closely at the box to see how Crayola had stabilized the built-in crayon sharpener under the tiers of crayons."
"But I'm trying to explain that I—" "I'm aware of your mitigating circumstances, but your negative attitude was excessive."
In a related use, it may visually indicate the shift between speakers when they overlap in speech. For example, the em dash is used this way inJoseph Heller'sCatch-22:
He was Cain, Ulysses, the Flying Dutchman; he was Lot in Sodom, Deirdre of the Sorrows, Sweeney in the nightingales among trees. He was the miracle ingredient Z-147. He was— "Crazy!" Clevinger interrupted, shrieking. "That's what you are! Crazy!" "—immense. I'm a real, slam-bang, honest-to-goodness, three-fisted humdinger. I'm a bona fide supraman."
Either anellipsis or an em dash can indicateaposiopesis, therhetorical device by which a sentence is stopped short not because of interruption, but because the speaker is too emotional or pensive to continue. Because the ellipsis is the more common choice, an em dash for this purpose may be ambiguous in expository text, as many readers would assume interruption, although it may be used to indicate great emotion in dramaticmonologue.
Long pause:
InEarly Modern English texts and afterward, em dashes have been used to add long pauses (as noted in Joseph Robertson's 1785An Essay on Punctuation):
Lord Cardinal! if thou think'st on heaven's bliss, Hold up thy hand, make signal of that hope.— He dies, and makes no sign!
This is aquotation dash. It may be distinct from an em dash in its coding (seehorizontal bar). It may be used to indicate turns in a dialogue, in which case each dash starts a paragraph.[46] It replaces other quotation marks and was preferred by authors such asJames Joyce:[47]
—O saints above! miss Douce said, sighed above her jumping rose. I wished I hadn't laughed so much. I feel all wet.
—O, miss Douce! miss Kennedy protested. You horrid thing!
The Walrus and the Carpenter Were walking close at hand; They wept like anything to see Such quantities of sand: "If this were only cleared away," They said, "it would be grand!"
An em dash may be used to indicate omitted letters in a word redacted to an initial or single letter or tofillet a word, by leaving the start and end letters whilst replacing the middle letters with a dash or dashes (forcensorship or simplydata anonymization). It may also censor the end letter. In this use, it is sometimes doubled.
It was alleged that D⸺ had been threatened with blackmail.
Three em dashes might be used to indicate a completely missing word.[48]
Three em dashes one after another can be used in a footnote, endnote, or another form of bibliographic entry to indicate repetition of the same author's name as that of the previous work,[48] which is similar to the use ofid.
According to most American sources (such asThe Chicago Manual of Style) and some British sources (such asThe Oxford Guide to Style), an em dash should always be set closed, meaning it should not be surrounded by spaces. But the practice in some parts of the English-speaking world, including the style recommended byThe New York Times Manual of Style and Usage for printed newspapers and theAP Stylebook, sets it open, separating it from its surrounding words by using spaces orhair spaces (U+200A) when it is being used parenthetically.[49][50] TheAP Stylebook rejects the use of the open em dash to set off introductory items in lists. However, the "space, en dash, space" sequence is the predominant style in German and Frenchtypography. (SeeEn dash versus em dash below.)
In Canada,The Canadian Style: A Guide to Writing and Editing,The Oxford Canadian A to Z of Grammar, Spelling & Punctuation: Guide to Canadian English Usage (2nd ed.),Editing Canadian English, and theCanadian Oxford Dictionary all specify that an em dash should be set closed when used between words, a word and numeral, or two numerals.
The Australian government'sStyle Manual for Authors, Editors and Printers (6th ed.), also specifies that em dashes inserted between words, a word and numeral, or two numerals, should be set closed. A section on the 2-em rule (⸺) also explains that the 2-em can be used to mark an abrupt break in direct or reported speech, but a space is used before the 2-em if a complete word is missing, while no space is used if part of a word exists before the sudden break. Two examples of this are as follows:
I distinctly heard him say, "Go away or I'll ⸺".
It was alleged that D⸺ had been threatened with blackmail.
Approximating the em dash with two or three hyphens
When an em dash is unavailable in a particularcharacter encoding environment—as in theASCII character set—it has usually beenapproximated as consecutive double (--) or triple (---) hyphen-minuses. The two-hyphen em dash proxy is perhaps more common, being a widespread convention in thetypewriting era. (It is still described for hard copy manuscript preparation inThe Chicago Manual of Style as of the 16th edition, although the manual conveys that typewritten manuscript and copyediting on paper are now dated practices.) The three-hyphen em dash proxy was popular with various publishers because the sequence of one, two, or three hyphens could then correspond to the hyphen, en dash, and em dash, respectively.
Because early comic bookletterers were not aware of the typographic convention of replacing a typewritten double hyphen with an em dash, the double hyphen became traditional in American comics. This practice has continued despite the development of computer lettering.[51][52]
These comparisons of thehyphen (-), n,en dash (–), m, andem dash (—), in various 12-point fonts, illustrate the typical relationship between lengths ("- n – m —"). In some fonts, the en dash is not much longer than the hyphen, and inLucida Grande, the en dash is actually shorter than the hyphen.
The en dash is wider than thehyphen but not as wide as the em dash. Anem width is defined as the point size of the currently used font, since the M character is not always the width of the point size.[53] In running text, various dash conventions are employed: an em dash—like so—or a spaced em dash — like so — or a spaced en dash – like so – can be seen in contemporary publications.
Various style guides and national varieties of languages prescribe different guidance on dashes. Dashes have been cited as being treated differently in the US and the UK, with the former preferring the use of an em dash with no additional spacing and the latter preferring a spaced en dash.[38] As examples of the US style,The Chicago Manual of Style andThe Publication Manual of the American Psychological Association recommend unspaced em dashes. Style guides outside the US are more variable. For example,The Elements of Typographic Style by Canadian typographerRobert Bringhurst recommends the spaced en dash – like so – and argues that the length and visual magnitude of an em dash "belongs to the padded and corseted aesthetic of Victorian typography".[8] In the United Kingdom, the spaced en dash is the house style for certain major publishers, including thePenguin Group, theCambridge University Press, andRoutledge. However, this convention is not universal. TheOxford Guide to Style (2002, section 5.10.10) acknowledges that the spaced en dash is used by "other British publishers" but states that theOxford University Press, like "most US publishers", uses the unspaced em dash.Fowler's Modern English Usage, saying that it is summarising theNew Hart's Rules, describes the principal uses of the em dash as "a single dash used to introduce an explanation or expansion" and "a pair of dashes used to indicate asides and parentheses", without stipulating whether it should be spaced but giving only unspaced examples.[54]
The en dash – always with spaces in running text when, as discussed in this section, indicating a parenthesis or pause – and the spaced em dash both have a certain technical advantage over the unspaced em dash. Most typesetting and word processing expects word spacing to vary to supportfull justification. Alone among punctuation that marks pauses or logical relations in text, the unspaced em dash disables this for the words it falls between. This can cause uneven spacing in the text, but can be mitigated by the use ofthin spaces,hair spaces, or evenzero-width spaces on the sides of the em dash. This provides the appearance of an unspaced em dash, but allows the words and dashes to break between lines. The spaced em dash risks introducing excessive separation of words. In full justification, the adjacent spaces may be stretched, and the separation of words further exaggerated. En dashes may also be preferred to em dashes when text is set in narrow columns, such as in newspapers and similar publications, since the en dash is smaller. In such cases, its use is based purely on space considerations and is not necessarily related to other typographical concerns.
On the other hand, a spaced en dash may be ambiguous when it is also used for ranges, for example, in dates or between geographical locations with internal spaces.
Thehorizontal bar (U+2015―HORIZONTAL BAR), also known as aquotation dash, is used to introduce quoted text. This is the standard method of printingdialogue in some languages. The em dash is equally suitable if the quotation dash is unavailable or is contrary to the house style being used.
There is no support in the standard TeX fonts, but one can use\hbox{---}\kern-.5em--- or an em dash.
Theswung dash (U+2053⁓SWUNG DASH) resembles a lengthenedtilde and is used to separate alternatives or approximates. Indictionaries, it is frequently used to stand in for the term being defined. A dictionary entry providing an example for the termhenceforth might employ the swung dash as follows:
henceforth (adv.) from this time forth; from now on; "⁓ she will be known as Mrs. Wales"
This table lists marks called a dash or that looks like a dash. The "Em and 5×" column uses a capital M as a standard comparison to demonstrate the vertical position of different Unicode dash characters. "5×" means that there are five copies of this type of dash.
Also called "hard hyphen",[citation needed] denotes a hyphen after which noword wrapping may apply. This is the case where the hyphen is part of atrigraph ortetragraph denoting a specific sound (like in the Swiss placename"S-chanf"), or where specific orthographic rules prevent a line break (like in Germancompounds of single-letter abbreviations and full nouns, as "E-Mail").
Similar to an en dash, but with exactly the width of a digit in the chosen typeface. The vertical position may also be centered on the zero digit, and thus higher than the en dash and em dash, which are appropriate for use with lowercase text in a vertical position similar to the hyphen. The figure dash may therefore be preferred to the en dash for indicating a closed range of values.[56]
Anarithmeticoperation used inmathematics to representsubtraction ornegative numbers. Its glyph is consistent with the glyph of the plus sign, and it is centred on the zero digit, unlike the ASCII hyphen-minus andU+2010‐HYPHEN, that (especially the latter) are designed to match lowercase letters and are inconsistent with arithmetic operators.
Wavy lines found in some East Asiancharacter sets. Typographically, they have the width of oneCJK character frame (fullwidth form), and follow the direction of the text, being horizontal for horizontal text, and vertical for columnar. They are used as dashes, and occasionally as emphatic variants of thekatakana vowel extender mark.
ASCII underscore, usually a horizontal line below thebaseline (i.e. a spacing underscore). It is commonly used withinURLs andidentifiers in programming languages, where a space-like separation between parts is desired but a real space is not appropriate. As usual for ASCII characters, this character shows a considerable range ofglyphic variation; therefore, whether sequences of this character connect depends on thefont used. See alsoU+FF3F＿FULLWIDTH LOW LINE
Used in programming languages (e.g. for thebitwise NOT operator inC and C++). Itsglyphic representation varies, therefore for punctuation in running text the use of more specific characters is preferred, seeabove.
Used to indicate where a linemay break, as in acompound word or between syllables.
U+00AF
¯
M¯¯¯¯¯
macron
A horizontal line positioned atcap height usually having the same length asU+005F_LOW LINE. It is a spacing character, related to the diacritic mark "macron". A sequence of such characters is not expected to connect, unlikeU+203E‾OVERLINE.
In many languages, such asPolish, the em dash is used as an openingquotation mark. There is no matching closing quotation mark; typically a new paragraph will be started, introduced by a dash, for each turn in the dialogue.[citation needed]
Corpus studies indicate that em dashes are more commonly used in Russian than in English.[59] In Russian, the em dash is used for the presentcopula (meaning 'am/is/are'), which is unpronounced in spoken Russian.
InFrench, em or en dashes can be used asparentheses (brackets), but the use of a second dash as a closing parenthesis is optional. When a closing dash is not used, the sentence is ended with a period (full-stop) as usual. Dashes are, however, much less common than parentheses.[citation needed]
InSpanish, em dashes can be used to mark off parenthetical phrases. Unlike in English, the em dashes are spaced like brackets, i.e., there is a space between main sentence and dash, but not between parenthetical phrase and dash.[60] For example: "Llevaba la fidelidad a su maestro—un buenprofesor— hasta extremos insospechados." (In English: 'He took his loyalty to his teacher—a goodteacher— to unsuspected extremes.')[61]
^Swift, Jonathan (1733).On Poetry; a rapsody. Printed at Dublin, reprinted at London. p. 8.
^"Dashes".MHRA Style Guide: A Handbook for Authors, Editors, and Writers of Theses (3rd ed.). London: Modern Humanities Research Association. 2020. § 5.2.Archived from the original on 2 April 2021. Retrieved2 April 2021.
^Garner, Bryan A. (2001).Legal Writing in Plain English: A Text with Exercises. Chicago Guides to Writing, Editing, and Publishing (illustrated, reprinted ed.).University of Chicago Press. p. 155.ISBN978-0-226-28418-7.Archived from the original on 1 August 2020. Retrieved1 July 2020 – via Google Books.Use an en-dash as an equivalent ofto (as when showing a span of pages), to express tension or difference, or to denote a pairing in which the elements carry equal weight.
^Dupré, Lynn (1998).Bugs in Writing (Revised ed.). Addison Wesley Longman. p. 221.ISBN978-0-201-37921-1.Archived from the original on 24 March 2021. Retrieved1 July 2020 – via Google Books.use en dashes when you have an equal-weighted pair serving as an adjective, such as love–hate relationship.
^abWill, Hill (2010).The Complete Typographer: A Foundation Course for Graphic Designers Working With Type (3rd ed.). Thames and Hudson.ISBN978-0-500-28894-8.
^Ritter, Robert M. (2002).The Oxford Guide to Style. Oxford University Press. p. 140.ISBN0-19-869175-0.The en rule is, as its name indicates, an en in length, which makes it longer than a hyphen and half the length of an em rule.
^"4.11.2 Em rule",New Hart's Rules: The Oxford Style Guide, Oxford University Press,archived from the original on 21 February 2015, retrieved21 February 2015
^Fowler, H. W.; Butterfield, Jeremy (2015).Fowler's dictionary of modern English usage (4th ed.). Oxford; New York, NY: Oxford University Press. pp. 201–202.ISBN978-0-19-966135-0.
