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In phonetics and phonology, gemination (//), or consonant lengthening, is an articulation of a consonant for a longer period of time than that of a single instance of the same type of consonant. It is distinct from stress. Gemination literally means "twinning" and comes from the same Latin root as "Gemini".
Consonant length is a distinctive feature in certain languages, such as Arabic, Berber, Maltese, Catalan, Danish, Estonian, Finnish, Classical Hebrew, Hindi, Hungarian, Italian, Japanese, Latin, Malayalam, Marathi, Tamil and Telugu. Other languages, such as the English language, do not have phonemic consonant geminates. Vowel length is distinctive in more languages than consonant length is.
Consonant gemination and vowel length are two different phenomena in languages like Arabic, Japanese, Finnish and Estonian; however, in languages like Italian, Norwegian and Swedish, vowel length and consonant length are interdependent.
Lengthened fricatives, nasals, laterals, approximants and trills are simply prolonged. In lengthened stops, the obstruction of the airway is prolonged, which delays release, and the "hold" is lengthened.
In terms of consonant duration, Berber and Finnish are reported to have a 3 to 1 ratio, compared with around 2 to 1 (or lower) in Japanese, Italian, and Turkish.
Gemination of consonants is distinctive in some languages and then is subject to various phonological constraints that depend on the language.
In some languages, like Italian, Swedish, Faroese, Icelandic, many Finnish dialects and Luganda, consonant length and vowel length depend on each other. A short vowel within a stressed syllable almost always precedes a long consonant or a consonant cluster, and a long vowel must be followed by a short consonant. In Classical Arabic, a long vowel was lengthened even more before permanently-geminate consonants.
In other languages, such as Finnish, consonant length and vowel length are independent of each other. In Finnish, both are phonemic; taka /taka/ "back", takka /takːa/ "fireplace" and taakka /taːkːa/ "burden" are different, unrelated words. Finnish consonant length is also affected by consonant gradation. Another important phenomenon is sandhi, which produces long consonants at word boundaries when there is an archiphonemic glottal stop |otaʔ se| > otas se "take it!"
In addition, in some Finnish compound words, if the initial word ends in an e, the initial consonant of the following word is geminated: jätesäkki "trash bag" [jætesːækːi], tervetuloa "welcome" [terʋetːuloa]. In certain cases, a v after a u is geminated by most people: ruuvi "screw" /ruːʋːi/, vauva "baby" [ʋauʋːa]. In the Tampere dialect, if a word receives gemination of v after u, the u is often deleted (ruuvi [ruʋːi], vauva [ʋaʋːa]), and lauantai "Saturday", for example, receives a medial v [lauʋantai], which can in turn lead to deletion of u ( [laʋːantai]).
Distinctive consonant length is usually restricted to certain consonants. There are very few languages that have initial consonant length; among them are Pattani Malay, Chuukese, Moroccan Arabic, a few Romance languages such as Sicilian and Neapolitan as well as many High Alemannic German dialects, such as that of Thurgovia. Some African languages, such as Setswana and Luganda, also have initial consonant length: it is very common in Luganda and indicates certain grammatical features. In colloquial Finnish and spoken Italian, long consonants are produced between words because of sandhi.
The difference between singleton and geminate consonants varies within and across languages. Sonorants show more distinct geminate-to-singleton ratios while sibilants have less distinct ratios. The bilabial and alveolar geminates are generally longer than velar ones.
The reverse of gemination reduces a long consonant to a short one, which is called degemination. It is a pattern in Baltic-Finnic consonant gradation that the strong grade (often the nominative) form of the word is degeminated into a weak grade (often all the other cases) form of the word: taakka > taakan (burden, of the burden). As a historical restructuring at the phonemic level, word-internal long consonants degeminated in Western Romance languages: e.g. Spanish /ˈboka/ 'mouth' vs. Italian /ˈbokka/, which continue Latin geminate /kk/.
Arabic marks gemination with a diacritic (ḥaraka) shaped like a rounded w, called the shadda (ـّ). It is written above the consonant that is to be doubled. It is sometimes used to avoid ambiguity in text that otherwise lacks diacritics, and is the diacritic most commonly used in this way: for example, a shadda can distinguish مدرّسة mudarrisa "female teacher" from مدرسة madrasa "school" (with full diacritics: مُدَرِّسَة and مَدْرَسَة).
In Berber, each consonant has a geminate counterpart, and gemination is lexically contrastive. The distinction between single and geminate consonants is attested in medial position as well as in absolute initial and final positions.
- ini "say"
- inni "those in question"
- akal "earth, soil"
- akkal "loss"
- imi "mouth"
- immi "mother"
- ifis "hyena"
- ifiss "he was quiet"
- tamda "pond, lake, oasis"
- tamedda "brown buzzard, hawk"
In addition to lexical geminates, Berber also has phonologically-derived and morphologically-derived geminates . Phonologically-derived geminates can surface by concatenation (e.g. [fas sin] 'give him two!') or by complete assimilation (e.g. /rad = k i-sli/ [rakk isli] 'he will touch you'). The morphological alternations include imperfective gemination, with some Berber verbs forming their imperfective stem by geminating one consonant in their perfective stem (e.g. [ftu] 'go! PF', [fttu] 'go! IMPF'), as well as quantity alternations between singular and plural forms (e.g. [afus] 'hand', [ifassn] 'hands').
In Catalan, geminates are expressed in writing with consonant repetition or the groups tn, tm, tl and tll, such as innecessari 'unnecessary', which is pronounced [inːəsəˈsaɾi] or ètnic (ethnic) setmana (week), atleta (athlete), rotllo (roll) etc. in careful speech. Gemination is not represented if it is purely phonetic, such as the assimilation occurring in tot bé /ˈtot ˈbe/ → [ˈtob ˈbe] 'all good'. Since the repetition of the letter l generates the digraph ll, which represents the phoneme /ʎ/, the geminate /ll/ is represented as two ls separated by a punt volat or centered dot (l·l):
- col·legi 'school'
- varicel·la 'chickenpox'
- mil·lenari 'millenary'
Danish has a three-way consonant length distinction. For instance:
- bunde [b̥ɔnə] "bottoms"
- bundne [b̥ɔnnə] "bound" (pl.)
- bundene [b̥ɔnn̩nə] "the bottoms"
The word bundene can phonemically be analyzed as /bɔnənə/, with the middle schwa being assimilated to [n].
- calm man [ˌkɑːmˈmæn]
- this saddle [ðɪsˈsædəl]
- midday [ˈmɪd.deɪ]
- lamppost [ˈlæmp.poʊst] (cf. lamb post, compost)
- cattail [ˈkæt.teɪl] (compare consonant length in "catfish")
- roommate [ˈrum.meɪt] (in some dialects)
- subbasement [ˌsʌbˈbeɪsmənt]
- evenness [ˈiːvənnəs]
- misspell [ˌmɪsˈspɛl]
- prime minister [ˌpraɪmˈmɪnɪstər]
With affricates, however, this does not occur. For instance:
- orange juice [ˈɒrɪndʒ.dʒuːs]
In most instances, the absence of this doubling does not affect the meaning, though it may confuse the listener momentarily. The following minimal pairs represent examples where the doubling does affect the meaning in most accents:
- fork handles versus four candles
- ten nails versus ten ales
- this sin versus this inn
- five alleys versus five valleys
- his own versus his zone
- unaimed [ʌnˈeɪmd] versus unnamed [ʌnˈneɪmd]
- foreigner [ˈfɔːrənər] versus forerunner [ˈfɔːrˌrənər] (only in some varieties of General American)
In some dialects gemination is also found when the suffix -ly follows a root ending in -l or -ll, as in:
- solely [ˈsoʊl.li]
In some varieties of Welsh English, the process takes place indiscriminately between vowels, e.g. in money [ˈmɜn.niː] but it also applies with graphemic duplication (thus, orthographically dictated), e.g. butter [ˈbɜt̚.tə]
In French, consonant length is usually not distinctive, but in certain exceptional cases it can be, such as the pair courons [kuʁɔ̃] vs courrons [kuʁːɔ̃]. Gemination also occurs in case of schwa elision.
In Ancient Greek, consonant length was distinctive, e.g., μέλω [mélɔː] "I am of interest" vs. μέλλω [mélːɔː] "I am going to". The distinction has been lost in the standard and most other varieties, with the exception of Cypriot (where it might carry over from Ancient Greek or arise from a number of synchronic and diachronic assimilatory processes, or even spontaneously), some varieties of the southeastern Aegean, and Italy.
- pattaa – leaf
- abbaa – father
- naqqaal – impersonator
- dajjaal – anti-Christ
- Dabbaa – box
- munnaa – young boy/baby
- gaddaa – mattress
For aspirated consonants, the geminate is formed by combining the corresponding non-aspirated consonant followed by its aspirated counterpart. There are few examples where an aspirated consonant is truly doubled.
- pat.thar – stone
- kat.thaa – brown spread on paan
- ad.dhaa – slang/short for half (aadhaa)
- mak.khii – fly
In Standard Italian, consonant strengthening is usually written with two consonants and it is distinctive. For example, bevve, meaning "he/she drank", is phonemically /ˈbevve/ and pronounced [ˈbevːe], while beve ("he/she drinks/is drinking") is /ˈbeve/, pronounced [ˈbeːve]. Tonic syllables are bimoraic and are therefore composed of either a long vowel in an open syllable (as in beve) or a short vowel in a closed syllable (as in bevve). In varieties with post-vocalic weakening of some consonants (e.g. /raˈdʒone/ → [raˈʒoːne] 'reason'), geminates are not affected (/ˈmaddʒo/ → [ˈmadːʒo] 'May').
Double or long consonants occur not only within words but also at word boundaries, and they are then pronounced but not necessarily written: chi + sa = chissà ("who knows") [kisˈsa] and vado a casa ("I am going home") [ˌvaːdo a kˈkaːsa] (the latter example refers to central and southern standard Italian). All consonants except /z/ can be geminated. This word-initial gemination is triggered either lexically by the item preceding the lengthening consonant (e.g. by preposition a 'to, at' in [akˈkaːsa] a casa 'homeward' but not by definite article la in [laˈkaːsa] la casa 'the house'), or by any word-final stressed vowel ([parˈlɔffranˈt͡ʃeːze] parlò francese 's/he spoke French' but [ˈparlafranˈt͡ʃeːze] parla francese 's/he speaks French').
In Latin, consonant length was distinctive, as in anus "old woman" vs. annus "year". Vowel length was also distinctive in Latin, but was not reflected in the orthography. Geminates inherited from Latin still exist in Italian, in which [ˈanːo] anno and [ˈaːno] ano contrast with regard to /nn/ and /n/ as in Latin. It has been almost completely lost in French and completely in Romanian. In West Iberian languages, former Latin geminate consonants often evolved to new phonemes, including some instances of nasal vowels in Portuguese and Old Galician as well as most cases of /ɲ/ and /ʎ/ in Spanish, but phonetic length of both consonants and vowels is no longer distinctive.
In Marathi, the compounding occurs quite frequently, as in the words haṭṭa (stubbornness), kaṭṭā (platform) or sattā (power). It seems to happen most commonly with the dental and retroflex consonants.
In Norwegian, gemination is indicated in writing by double consonants. Gemination often differentiates between otherwise unrelated words.
- måte Norwegian pronunciation: [[Help:IPA/Norwegian|ˈmɔːtə]] / måtte Norwegian pronunciation: [[Help:IPA/Norwegian|ˈmotːə]] – "method" / "had to"
- lete Norwegian pronunciation: [[Help:IPA/Norwegian|ˈleːtə]] / lette Norwegian pronunciation: [[Help:IPA/Norwegian|ˈlɛtːə]] – "search" / "take off"
- sine Norwegian pronunciation: [[Help:IPA/Norwegian|ˈsiːnə]] / sinne Norwegian pronunciation: [[Help:IPA/Norwegian|ˈsɪnːə]] – "theirs" / "anger"
In Polish, consonant length is indicated with two identical letters. Examples:
- wanna /ˈvanːa/ – "bathtub"
- Anna /ˈanːa/
- horror /ˈxɔrːɔr/ – "horror"
- hobby /ˈxɔbːɨ/ – "hobby"
Consonant length is distinctive and sometimes is necessary to distinguish words:
- rodziny /rɔˈd͡ʑinɨ/ – "families"; rodzinny /rɔˈd͡ʑinːɨ/ – adjective of "family"
- saki /saki/ – "sacks, bags"; ssaki /sːaki/ – "mammals",
- leki /ˈlɛkʲi/ – "medicines"; lekki /ˈlɛkʲːi/ – "light, lightweight"
Double consonants are common on morpheme borders where the initial or final sound of the suffix is the same as the final or initial sound of the stem (depending on the position of the suffix). Examples:
- przedtem /ˈpʂɛtːɛm/ – "before, previously"; from przed (suffix "before") + tem (archaic "that")
- oddać /ˈɔdːat͡ɕ/ – "give back"; from od (suffix "from") + dać ("give")
- bagienny /baˈgʲɛnːɨ/ – "swampy"; from bagno ("swamp") + ny (suffix forming adjectives)
- najjaśniejszy /najːaɕˈɲɛ̯iʂɨ/ – "brightest"; from naj (suffix forming superlative) + jaśniejszy ("brighter")
Punjabi in its official script Gurmukhi uses a diacritic called an áddak ( ੱ ) (ਅੱਧਕ, [ə́dːək]) which is written above the word and indicates that the following consonant is geminate. Gemination is specially characteristic of Punjabi compared to other Indo-Aryan languages like Hindi-Urdu, where instead of the presence of consonant lengthening, the preceding vowel tends to be lengthened. Consonant length is distinctive in Punjabi, for example:
- ਦਸ [d̪əs] – 'ten'; ਦੱਸ [d̪əsː] – 'tell' (verb)
- ਪਤਾ [pət̪a] – 'aware of something'; 'ਪੱਤਾ [pət̪ːa] – 'leaf'
- ਸਤ [sət̪] – 'truth' (liturgical); ਸੱਤ [sət̪ː] – 'seven'
- ਕਲਾ [kəla] – 'art'; ਕੱਲਾ [kəlːa] – 'alone'
In Russian, consonant length (indicated with two letters, as in ванна [ˈvannə] 'bathtub') may occur in several situations.
Minimal pairs (or chronemes) exist, such as подержать [pədʲɪrˈʐatʲ] 'to hold' vs поддержать [pədʲːɪrˈʐatʲ] 'to support', and their conjugations, or длина [dlʲɪˈna] 'length' vs длинна [dlʲɪˈnːa] 'long' adj. f.
- Word formation or conjugation: длина ([dlʲɪˈna] 'length') > длинный ([ˈdlʲinnɨj] 'long') This occurs when two adjacent morphemes have the same consonant and is comparable to the situation of Polish described above.
- Assimilation. The spelling usually reflects the unassimilated consonants, but they are pronounced as a single long consonant.
- высший ([ˈvɨʂːɨj] 'highest').
In Ukrainian, geminates are found between vowels: багаття /bɑˈɦɑtʲːɑ/ "bonfire", подружжя /poˈdruʒʲːɑ/ "married couple", обличчя /obˈlɪt͡ʃʲːɑ/ "face". Geminates also occur at the start of a few words: лляний /lʲːɑˈnɪj/ "flaxen", forms of the verb лити "to pour" (ллю /lʲːu/, ллєш /lʲːɛʃ/ etc.), ссати /ˈsːɑtɪ/ "to suck" and derivatives. Gemination is in some cases semantically crucial; for example, манна means "manna" or "semolina" while мана means "delusion".
Luganda is unusual in that gemination can occur word-initially, as well as word-medially. For example, kkapa /kːapa/ 'cat', /ɟːaɟːa/ jjajja 'grandfather' and /ɲːabo/ nnyabo 'madam' all begin with geminate consonants.
There are three consonants that cannot be geminated: /j/, /w/ and /l/. Whenever morphological rules would geminate these consonants, /j/ and /w/ are prefixed with /ɡ/, and /l/ changes to /d/. For example:
- -ye /je/ 'army' (root) > ggye /ɟːe/ 'an army' (noun)
- -yinja /jiːɲɟa/ 'stone' (root) > jjinja /ɟːiːɲɟa/ 'a stone' (noun); jj is usually spelt ggy
- -wanga /waːŋɡa/ 'nation' (root) > ggwanga /ɡːwaːŋɡa/ 'a nation' (noun)
- -lagala /laɡala/ 'medicine' (root) > ddagala /dːaɡala/ 'medicine' (noun)
In Japanese, consonant length is distinctive (as is vowel length). Gemination in the syllabary is represented with the sokuon, a small tsu: っ for hiragana in native words and ッ for katakana in foreign words. For example, 来た (きた, kita) means "came; arrived", while 切った (きった, kitta) means "cut; sliced". With the influx of gairaigo ("foreign words") into Modern Japanese, voiced consonants have become able to geminate as well: バグ (bagu) means "(computer) bug", and バッグ (baggu) means "bag". Distinction between voiceless gemination and voiced gemination is visible in pairs of words such as キット (kitto, meaning "kit") and キッド (kiddo, meaning "kid"). In addition, in some variants of colloquial Modern Japanese, gemination may be applied to some adjectives and adverbs (regardless of voicing) in order to add emphasis: すごい (sugoi, "amazing") contrasts with すっごい (suggoi, "really amazing"); 思い切り (おもいきり, omoikiri, "with all one's strength") contrasts with 思いっ切り (おもいっきり, omoikkiri, "really with all one's strength").
- müderrise [myˈdeɾːise] ([from Arabic, mostly obsolete] "female teacher")
- pizza [piˈzːa] (from Italian)
Loanwords originally ending with a geminated consonant are always written and pronounced without the ending gemination.
Although gemination is resurrected when the word takes a suffix.
- hac becomes hacca [haˈdʒːa] (to hajj) when it takes the suffix "-a" (to, indicating destination)
- hat becomes hattın [haˈtːɯn] (of calligraphy) when it takes the suffix "-ın" (of, expressing possession)
Gemination also occurs when a suffix starting with a consonant comes after a word that ends with the same consonant.
- el [el] (hand) + -ler [leɾ] ("-s", marks plural) = eller [eˈlːeɾ] (hands). (contrasts with eler, s/he eliminates)
- at [at] (to throw) + -tık [tɯk] ("-ed", marks past tense, first person plural) = attık [aˈtːɯk] (we threw [smth.]). (contrasts with atık, waste)
Consider following example:
- മേശ + പെട്ടി (mēśa + peṭṭi) – മേശപ്പെട്ടി (mēśappeṭṭi)
Estonian has three phonemic lengths; however, the third length is a suprasegmental feature, which is as much tonal patterning as a length distinction. It is traceable to allophony caused by now-deleted suffixes, for example half-long linna < *linnan "of the city" vs. overlong linna < *linnahan "to the city".[clarification needed]
Consonant length is phonemic in Finnish: For example, takka [ˈtakːa] (transcribed with the length sign [ː] or with a doubled sign [ˈtakka]), 'fireplace', but taka [ˈtaka], 'back'. Consonant gemination occurs with simple consonants (hakaa : hakkaa) and between syllables in the pattern (consonant)-vowel-sonorant-stop-stop-vowel (palkka), but not generally in codas or with longer syllables. (This occurs in Sami languages, so there is the name of Sami origin Jouhkki).
Sandhi may also produce geminates. Consonant and vowel gemination are both phonemic and occur independently, e.g. Mali, maali, malli, maallinen (Mali (a Karelian surname), paint, model and secular, respectively).
In multiple Finnish dialects there are also types of special gemination when in contact with long vowels: Southwestern special gemination ("Lounaismurteiden erikoisgeminaatio") (lengthening of stops+shortening of long vowel), with the type Leipää< Leippä, the "Common gemination" ("Yleisgeminaatio") (all consonants in short, stressed syllables are lengthened), with the type Putoaa > Puttoo, and its extension (which is strongest in the northwestern Savonian dialects), the "Eastern dialectal special gemination" ("Itämurteiden erikoisgeminaatio") (same as the Common gradation, but applies also to unstressed syllables and certain clusters), with the types Lehmiä > Lehmmii and Maksetaan > Maksettaan.
Most Sami languages contrast three different degrees of consonant length. These often contrast in different forms within a single inflectional paradigm, as in Northern Sami goarˈrut "let's sew!" versus goarrut "to sew, we sew" versus goarut "you (sg.) sew". Often, progressively longer consonants correspond to a progressively shorter preceding vowel.
In Proto-Samic, the common ancestor of the Sami languages, there was already a contrast between single and geminate consonants, inherited from Proto-Uralic. A process called consonant gradation then lengthened all consonants when they stood at the end of a stressed syllable, if the next syllable was open. The subsequent loss of final consonants and vowels in the later Sami languages made this process contrastive, resulting in as many as four contrastive lengths (lengthened geminate, unlengthened geminate, lengthened single, unlengthened single). The modern Sami languages have reduced this to three, by merging the unlengthened geminates with the lengthened single consonants.
In Wagiman, an indigenous Australian language, consonant length in stops is the primary phonetic feature that differentiates fortis and lenis stops. Wagiman does not have phonetic voice. Word-initial and word-final stops never contrast for length.
In written language, consonant length is often indicated by writing a consonant twice (ss, kk, pp, and so forth), but can also be indicated with a special symbol, such as the shadda in Arabic, the dagesh in Classical Hebrew, or the sokuon in Japanese. Estonian uses b, d, g for short consonants, and p, t, k and pp, tt, kk are used for long consonants.
In the International Phonetic Alphabet, long consonants are normally written using the triangular colon ː, e.g. penne [penːe] ('feathers', 'pens', also a kind of pasta), though doubled letters are also used (especially for underlying phonemic forms, or in tone languages to facilitate diacritic marking).
- Catalan uses the raised dot (called an "interpunct") to distinguish a geminated l from a palatal ll. Thus, paral·lel ("parallel") and Llull (Standard Catalan: [pəɾəlˈlɛl], [ʎuʎ]).
- Hungarian digraphs and trigraphs are geminated by doubling the first letter only, thus the geminate form of sz /s/ is ssz /sː/ (rather than *szsz), and that of dzs /d͡ʒ/ is ddzs /d͡ʒː/.
- The only digraph in Ganda, ny /ɲ/ is doubled in the same way: nny /ɲː/.
- In Italian, geminated instances of the sound cluster [kw] (represented by the digraph qu) are always indicated by writing cq, except in the words soqquadro and beqquadro, where the letter q is doubled. The gemination of sounds [ɲ], [ʃ] and [ʎ], (spelled gn, sc(i), and gl(i), respectively) is not indicated because these consonants are always geminated when occurring between vowels. Also the sounds [ts], [dz] (both spelled z) are always geminated when occurring between vowels, yet their gemination is sometimes shown, redundantly, by doubling the z as, e.g., in pizza [ˈpitsːa].
- In Swedish and Norwegian, the general rule is that a geminated consonant is written double, unless succeeded by another consonant. Hence hall ("hall"), but halt ("Halt!"). In Swedish, this does not apply to morphological changes (so kall, "cold" and kallt, "coldly" or compounds [so tunnbröd ("flatbread")]. The exception are some words ending in -m, thus hem ["home"] [but hemma ("at home")] and stam ["stem"], but lamm ["lamb", to distinguish the word from lam ("lame")], with a long /a/), as well as adjectives in -nn, so tunn, "thin" but tunt, "thinly" (whilst Norwegian has a rule always prohibiting two "m"s at the end of a word (with the exception being only a handful of proper names, and as a rule forms with suffixes reinsert the second "m", and the rule is that these word-final "m"s always cause the preceding vowel sound to be short (despite the spelling)).
Other representations of double lettersEdit
Doubled orthographic consonants do not always indicate a long phonetic consonant.
- In English, for example, the [n] sound of "running" is not lengthened. Consonant digraphs are used in English to indicate the preceding vowel is a short (lax) vowel, while a single letter often allows a long (tense) vowel to occur. For example, "tapping" /tæpɪŋ/ (from "tap") has a short a /æ/, which is distinct from the diphthongal long a /eɪ/ in "taping" /teɪpɪŋ/ (from "tape").
- In Standard Modern Greek, doubled orthographic consonants have no phonetic significance at all.
- Hangul (the Korean alphabet) and its romanizations also use double consonants, but to indicate fortis articulation, not gemination.
- In Japanese, germination is denoted by placing the small variant of the syllable Tsu (っ or ッ) between two syllables, of the same script, where the end syllable must begin with a consonant.
- Khattab, Ghada & Al-Tamimi, Jalal. (2014). Geminate timing in Lebanese Arabic: The relationship between phonetic timing and phonological structure. Laboratory Phonology, 5(2), 231-269.
- Blust, Robert. (2013). The Austronesian Languages (Rev. ed.). Australian National University.
- Ben Hedia S (2019). Gemination and degemination in English affixation: Investigating the interplay between morphology, phonology and phonetics (pdf). Berlin: Language Science Press. doi:10.5281/zenodo.3232849. ISBN 978-3-96110-188-7.
- Crystal, David (2003). The Cambridge Encyclopedia of the English Language Second Edition, Cambridge University Press, p. 335
- "Raddoppiamenti di vocali e di consonanti". Dizionario italiano d'ortografia e pronunzia (DOP). RAI. 2009. Retrieved November 11, 2009.
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