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Romance verbs are the most inflected part of speech in the language family. In the transition from Latin to the Romance languages, verbs went through many phonological, syntactic, and semantic changes. Most of the distinctions present in classical Latin continued to be made, but synthetic forms were often replaced with more analytic ones. Other verb forms changed meaning, and new forms also appeared.

The following table presents a comparison of the conjugation of the regular verb cantare "to sing" in Classical Latin, and Vulgar Latin (reconstructed as Proto-Italo-Western Romance, with stress marked), and nine modern Romance languages. The conjugations below were given from their respective Wiktionary pages.

The comparison of Romance conjugations of the verb "to sing"

Form		Classical Latin	Vulgar Latin		Major languages							Minor languages
					Spanish	Portuguese	Italian	French (written)[a]	French (spoken)[a]	Romanian		Sardinian (Logudorese)	Sicilian	Catalan	Romansh (Grischun)
Infinitive		cantāre	*cantáre		cantar	cantar	cantare	chanter	/ʃɑ̃te/	cânta		cantare	cantari	cantar	chantar
Present participle[b]		cantandus	*cantándo		cantando	cantando	cantando	chantant	/ʃɑ̃tɑ̃/	cântând		–	cantannu	cantant	chantond
		cantāns	*cantánte		cantante	cantante	cantante[c]	–	–	–		cantende	–	–	–
Past participle		cantātum	*cantáto		cantado	cantado	cantato	chanté	/ʃɑ̃te/	cântat		cantadu	cantatu	cantat	chantà
Indicative	Present	cantō cantās cantat cantāmus cantātis cantant	*cánto *cántas *cántat *cantámos *cantátes *cántant		canto cantas canta cantamos cantáis cantan	canto cantas canta cantamos cantais cantam	canto canti canta cantiamo cantate cantano	chante chantes chante chantons chantez chantent	/ʃɑ̃t/ /ʃɑ̃t/ /ʃɑ̃t/ /ʃɑ̃tɔ̃/ /ʃɑ̃te/ /ʃɑ̃t/	cânt cânți cântă cântăm cântați cântă		canto cantas cantat cantamus cantades cantant	cantu canti canta cantamu cantati càntanu	canto cantes canta cantem canteu canten	chant chantas chanta chantain chantais chantan
	Imperfect	cantābam cantābās cantābat cantābāmus cantābātis cantābant	*cantába *cantábas *cantábat *cantábamos *cantábates *cantábant		cantaba cantabas cantaba cantábamos cantabais cantaban	cantava cantavas cantava cantávamos cantáveis cantavam	cantavo cantavi cantava cantavamo cantavate cantavano	chantais chantais chantait chantions chantiez chantaient	/ʃɑ̃tɛ/ /ʃɑ̃tɛ/ /ʃɑ̃tɛ/ /ʃɑ̃tjɔ̃/ /ʃɑ̃tje/ /ʃɑ̃tɛ/	cântam cântai cânta cântam cântați cântau		cantaia cantaias cantaiat cantaiamus cantaiades cantaiant	cantavu cantavi cantava cantàvamu cantàvavu cantàvanu	cantava cantaves cantava cantàvem cantàveu cantaven	chantava chantavas chantava chantavan chantavas chantavan
	Preterite	cantāvī cantāvistī cantāvit cantāvimus cantāvistis cantāvērunt	*cantái *cantásti *cantáut *cantámos *cantástes *cantáront		canté cantaste cantó cantamos cantasteis cantaron	cantei cantaste cantou cantámos cantastes cantaram	cantai cantasti cantò cantammo cantaste cantarono	chantai chantas chanta chantâmes chantâtes chantèrent[d]	/ʃɑ̃te/ /ʃɑ̃ta/ /ʃɑ̃ta/ /ʃɑ̃tam/ /ʃɑ̃tat/ /ʃɑ̃tɛʁ/	cântai cântași cântă cântarăm cântarăți cântară		cantesi cantesti cantesit cantemus cantezis canteint	cantai cantasti cantau cantammu cantastivu cantàrunu	cantí cantares cantà cantàrem cantàreu cantaren	–
	Pluperfect	cantāveram cantāveras cantāverat cantāverāmus cantāverātis cantāverant	*cantára *cantáras *cantárat *cantáramos *cantárates *cantárant		cantara cantaras cantara cantáramos cantarais cantaran[e]	cantara cantaras cantara cantáramos cantáreis cantaram[f]	–	–	–	–		–	cantirìa cantirissi cantirìa cantirìamu cantirìavu cantirìanu[g]	–	–
	Future[h]	cantābō cantābis cantābit cantābimus cantābitis cantābunt	–		cantaré cantarás cantará cantaremos cantaréis cantarán	cantarei cantarás cantará cantaremos cantareis cantarão	canterò canterai canterà canteremo canterete canteranno	chanterai chanteras chantera chanterons chanterez chanteront	/ʃɑ̃tʁe/ /ʃɑ̃tʁa/ /ʃɑ̃tʁa/ /ʃɑ̃tʁɔ̃/ /ʃɑ̃tʁe/ /ʃɑ̃tʁɔ̃/	–		–	cantirò cantirai cantirà cantiremu cantireti cantirannu	cantaré cantaràs cantarà cantarem cantareu cantaran	–
	Conditional (Future in the past)[h]	–	–		cantaría cantarías cantaría cantaríamos cantaríais cantarían	cantaria cantarias cantaria cantaríamos cantaríeis cantariam	canterei canteresti canterebbe canteremmo cantereste canterebbero	chanterais chanterais chanterait chanterions chanteriez chanteraient	/ʃɑ̃tʁɛ/ /ʃɑ̃tʁɛ/ /ʃɑ̃tʁɛ/ /ʃɑ̃təʁjɔ̃/ /ʃɑ̃təʁje/ /ʃɑ̃tʁɛ/	–		–	cantirìa cantirissi cantirìa cantirìamu cantirìavu cantirìanu	cantaria cantaries cantaria cantaríem cantaríeu cantarien	–
	Future perfect	cantāverō cantāveris cantāverit cantāverimus cantāveritis cantāverint	*cantáre *cantáres *cantáret *cantáremos *cantáretes *cantárent		cantare cantares cantare cantáremos cantareis cantaren[i][j]	cantar cantares cantar cantarmos cantardes cantarem[i]	–	–	–	–		–	–	–	–
Subjunctive	Present	cantem cantēs cantet cantēmus cantētis cantent	*cánte *cántes *cántet *cantémos *cantétes *cántent		cante cantes cante cantemos cantéis canten	cante cantes cante cantemos canteis cantem	canti canti canti cantiamo cantiate cantino	chante chantes chante chantions chantiez chantent	/ʃɑ̃t/ /ʃɑ̃t/ /ʃɑ̃t/ /ʃɑ̃tjɔ̃/ /ʃɑ̃tje/ /ʃɑ̃t/	cânt cânți cânte cântăm cântați cânte		cante cantes cantet cantemus cantedes cantent	cantu canti canta cantamu cantati càntanu	canti canti canta cantem canteu cantin	chantia chantias chantia chantian chantias chantian
	Perfect	cantāverim cantāveris cantāverit cantāverimus cantāveritis cantāverint	–		–	–	–	–	–	–		–	–	–	–
	Imperfect	cantārem cantārēs cantāret cantārēmus cantārētis cantārent	*cantáre *cantáres *cantáret *cantáremos *cantáretes *cantárent		–	cantar cantares cantar cantarmos cantardes cantarem[k]	–	–	–	–		cantere canteres canteret canteremus canterezes canterent	–	–	–
	Pluperfect[l]	cantāvissem cantāvissēs cantāvisset cantāvissēmus cantāvissētis cantāvissent	*cantásse *cantásses *cantásset *cantássemos *cantássetes *cantássent		cantase cantases cantase cantásemos cantaseis cantasen	cantasse cantasses cantasse cantássemos cantásseis cantassem	cantassi cantassi cantasse cantassimo cantaste cantassero	chantasse chantasses chantât chantassions chantassiez chantassent[j]	/ʃɑ̃tas/ /ʃɑ̃tas/ /ʃɑ̃ta/ /ʃɑ̃tasjɔ̃/ /ʃɑ̃tasje/ /ʃɑ̃tas/	cântasem cântaseși cântase cântaserăm cântaserăți cântaseră		–	cantassi cantassi cantassi cantàssimu cantàssivu cantàssiru	cantés cantessis cantmés cantéssim cantéssiu cantessin	chantass chantasses chantass chantassen chantasses chantassen[m]
Imperative[n]		cantā cantāte	*cánta *cantáte		canta cantad	canta cantai	canta cantate	chante chantez	/ʃɑ̃t/ /ʃɑ̃te/	cântă cântați		canta cantade	canta cantati	canta canteu	chanta chantai

Note that the Vulgar Latin reconstructions are believed to have regularized word stress within each tense (except the present and imperative). Word-final ⟨e⟩ probably converged on /ə/. Many verb forms have undergone elisions, like the indicative pluperfect cantāveram > *cantára and the subjunctive imperfect cantāvissem > *cantásse.

In this section, "Vulgar Latin" is actually reconstructed as reconstructed Proto-Italo-Western Romance, most notably the shift from Classical Latin -i- and -u- to -e- /e/ and -o- /o/, as opposed to inherited /ɛ/ and /ɔ/ respectively. The developments include:

• The -v- of the perfect tenses were dropped or elided, but sometimes become /u/ after vowels.
• The past participle were sometimes sporadically rounded to *-ū-, this situation is preserved in French.
• The "unstressed" indicative imperfect is very likely from shortened *-bămus, *-bătis, yielding to the stress on the third-from-last syllable (cantā́bămus), as opposed to Classical Latin stress on the second-from-last syllable (cantābā́mus). Languages which retain this irregular stress were the languages of Iberia, Sicilian, and French.
• Romance metaphony. In forms containing -ī next to mid-open vowels, especially in preterite forms were heightened.

In the Proto-Romance grammatical tradition, the second and third conjugation are known as third conjugation, similarly to French.

Verbs in the first conjugation are in -āre (*-áre), later evolved to -are in Italian, -ar in most Romance languages and -er in French.

Vulgar Latin conjugation of *-áre

Infinitive		*-áre
Present participle		*-ánte
Gerund		*-ándo
Supine		*-áto
		1st singular	2nd singular	3rd singular	1st plural	2nd plural	3rd plural
Indicative	Present	*-o[a]	*-as[a]	*-at[a]	*-ámos	*-átes	*-ant[a]
	Imperfect	*-ába	*-ábas	*-ábat	*-ábamos	*-ábates	*-ábant
	Preterite	*-áui	*-áusti	*-áut	*-ámos	*-ástes	*-áront
	Pluperfect	*-ára	*-áras	*-árat	*-áramos	*-árates	*-árant
	Future perfect	*-áro	*-áres	*-áret	*-áremos	*-áretes	*-árent
Subjunctive	Present	*-e[a]	*-es[a]	*-et[a]	*-émos	*-étes	*-ent[a]
	Imperfect	*-áre	*-áres	*-áret	*-arémos	*-arétes	*-árent
	Pluperfect	*-ásse	*-ásses	*-ásset	*-assémos	*-assétes	*-ássent
Imperative			*-a[a]			*-áte
^ a b c d e f g h i Causes the previous syllable to be stressed (*amáre → *ámo).

Verbs in the second conjugation are in -ēre (*-ére), later evolved to -ere in Italian, -er in most Romance languages and -oir in French (no "regular" -oir verbs). Another infinitive -ere has merged into this paradigm.

Vulgar Latin conjugation of *-ére

Infinitive		*-ére
Present participle		*-énte
Gerund		*-éndo
Supine		*-eto[a]
		1st singular	2nd singular	3rd singular	1st plural	2nd plural	3rd plural
Indicative	Present	*-io[a]	*-es[a]	*-et[a]	*-émos	*-étes	*-ent[a]
	Imperfect	*-éba	*-ébas	*-ébat	*-ébamos	*-ébates	*-ébant
	Preterite	*-í	*-ísti	*-ét	*-émos	*-éstes	*-éront
	Pluperfect	*-éra	*-éras	*-érat	*-éramos	*-érates	*-érant
	Future perfect	*-éro	*-éres	*-éret	*-éremos	*-éretes	*-érent
Subjunctive	Present	*-ia[a]	*-ias[a]	*-iat[a]	*-iámos	*-iátes	*-iant[a]
	Imperfect	*-ére	*-éres	*-éret	*-éremos	*-éretes	*-érent
	Pluperfect	*-ésse	*-ésses	*-ésset	*-essémos	*-essétes	*-éssent
Imperative			*-é[a]			*-éte
^ a b c d e f g h i j Causes the previous syllable to be stressed (*amáre → *ámo).

Verbs in the third conjugation are in -ere (*-ere, caused stress in previous syllable), later merged with -ere (*-ere, causes stress in antepenultimate syllable), but -re in French and Catalan. The suffix -re in French are in the third group, also known as irregular verbs.

The -iō variant (*-io in Vulgar Latin) now defunct, later merged with the second conjugation; the paradigm now only exists in some descendants of the verb faciō.

Vulgar Latin conjugation of *-ere

Infinitive		*-ere[a]
Present participle		*-énte
Gerund		*-éndo
Supine		*-eto[a]
		1st singular	2nd singular	3rd singular	1st plural	2nd plural	3rd plural
Indicative	Present	*-o[a]	*-es[a]	*-et[a]	*-émos	*-étes	*-ont[a]
	Imperfect	*-éba	*-ébas	*-ébat	*-ébamos	*-ébates	*-ébant
	Preterite	*-í	*-ísti	*-ét	*-émos	*-éstes	*-érent
	Pluperfect	*-éra	*-éras	*-érat	*-éramos	*-érates	*-érant
	Future perfect	*-éro	*-éres	*-éret	*-éremos	*-éretes	*-érent
Subjunctive	Present	*-a[a]	*-as[a]	*-at[a]	*-ámos	*-átes	*-ant[a]
	Imperfect	*-ére	*-éres	*-éret	*-éremos	*-éretes	*-érent
	Pluperfect	*-ésse	*-ésses	*-ésset	*-essémos	*-essétes	*-éssent
Imperative			*-e[a]			*-éte
^ a b c d e f g h i j k Causes the previous syllable to be stressed (*amáre → *ámo).

Verbs in the fourth conjugation are in -īre (*-íre), later evolved to -ire in Italian, and -ir in most Romance languages. This conjugation type are infixed with once-inchoative -īsc- → *-ísc- in some languages, but its placement varies.

Vulgar Latin conjugation of *-íre

Infinitive		*-íre
Present participle		*-iénte
Gerund		*-iéndo
Supine		*-íto
		1st singular	2nd singular	3rd singular	1st plural	2nd plural	3rd plural
Indicative	Present	*-io[a]	*-is[a]	*-it[a]	*-ímos	*-ítes	*-iont[a]
	Imperfect	*-iéba	*-iébas	*-iébat	*-iébamos	*-iébates	*-iébant
	Preterite	*-i	*-ísti	*-it	*-ímos	*-ístes	*-íront
	Pluperfect	*-íra	*-íras	*-írat	*-íramos	*-írates	*-írant
	Future perfect	*-íro	*-íres	*-íret	*-íremos	*-íretes	*-írent
Subjunctive	Present	*-ia[a]	*-ias[a]	*-iat[a]	*-iamos	*-iates	*-iant[a]
	Imperfect	*-íre	*-íres	*-íret	*-íremos	*-íretes	*-írent
	Pluperfect	*-ísse	*-ísses	*-ísset	*-íssemos	*-íssetes	*-íssent
Imperative			*-i[a]			*-íte
^ a b c d e f g h i Causes the previous syllable to be stressed (*amáre → *ámo).

In Italian, Catalan, and Romanian, the infix -isc-; -esc-, -eix- (Catalan), and -ăsc- (Romanian) is placed on once-stressed indicative and subjunctive present forms (the first-, second-, third-singular and third plural present tenses), and stressed imperatives. In French, the infix -iss- is placed on all indicative present forms, the indicative imperfect, the subjunctive present, and plural imperatives.

While there are few non-infixed -īre verbs (also known are pure -īre verbs), in French the infixed verbs are the only regular verbs, otherwise irregular.

While the nominal morphology in Romance languages is primarily agglutinative, the verbal morphology is fusional. The verbs are highly inflected for numbers (singular and plural), persons (first-, second-, and third-person), moods (indicative, conditional, subjunctive, and imperative), tenses (present, past, future), and aspects (imperfective and perfective).

Because of the complexities in Romance conjugation, certain languages have a separate article regarding these conjugations:

• Italian conjugation
• Spanish verbs
• Portuguese verb conjugation
• Romanian verbs
• French conjugation
• Catalan verbs
• Occitan conjugation
• Sardinian conjugation

While there are 4 regular infinitives in Classical Latin, namely -āre, -ēre, -ere, and -īre, some of these infinitive were merged. In many Romance languages including Spanish and Portuguese, the main infinitives are -ar, -er, and -ir, with addition of -ôr (Portuguese only) which only exists in the verb pôr, traditionally considered as -er verbs. While in Italian, the infinitives are -are, -ere, -ire. The infinitives -er and -ere (Italian) resulted from the merge of Latin infinitives -ēre and -ere. In French, the infinitives are -er, -oir, -re, -ir, but verbs with -oir and -re are in the third group, also known as irregular verbs.

Latin deponent verbs like sequor and nascor (infinitive sequī, nascī) changed to active counterparts *séquo and *násco (infinitive *séquere, *nascere), as in Portuguese seguir, Spanish seguir, and Italian seguire; and Portuguese nascer, Spanish nacer, and French naître.

Spanish

Hard		Soft
Back vowels	Front vowels	Back vowels	Front vowels
c-	quV-	z-	c-
g-	guV-	j-	g-

In many Romance languages, verb stems ending in -c, -z shown above were regularly altered to preserve its pronunciation. However, it is not considered irregular.

While the passive voice became completely periphrastic in Romance, the active voice has been morphologically preserved to a greater or lesser extent. The tables below compare the conjugation of the Latin verbs sum and stō in the active voice with that of the Romance copulae, their descendants. For simplicity, only the first person singular is listed for finite forms. Note that certain forms in Romance languages come from the suppletive sources sedeo (to be seated) instead of sum, e.g. subjunctive present: sedea > sia, sea, seja... (medieval Galician-Portuguese, for instance, had double forms in the whole conjugation: sou/sejo, era/sia, fui/sevi, fora/severa, fosse/sevesse...)

Form		Latin			Italian		French1		Spanish		Portuguese		Logudorese		Catalan		Sicilian		Romansh	Romanian
Indicative	Present	sum	stō		sono	sto	suis	–	soy	estoy	sou	estou	so	isto	sóc	estic	sugnu	staiu	sun	sunt
	Imperfect	eram	stābam		ero	stavo	–	étais	era	estaba	era	estava	essia	istaia	era	estava	era	stava	era	eram
	Preterite	fuī	stetī		fui	stetti	fus	–	fui	estuve	fui	estive	essesi	istesi	fui	estiguí	fui	stesi	–	fui, fusei
	Pluperfect	fueram	steteram		–	–	–	–	fuera	estuviera	fora	estivera	–	–	fóra	estigués	fora	–	–	–
	Future2	erō	stābō		sarò	starò	serai	–	seré	estaré	serei	estarei	–	–	seré	estaré	–	–	–	–
Subjunctive	Present	sim	stem		sia	stia	sois	–	sea	esté	seja	esteja	sia	iste	sigui, siga	estigui, estiga	–	–	saja	să fiu
	Perfect3	fuerim	steterim		–	–	–	–	fuere	estuviere	for	estiver	–	–	–	–	–	–	–	–
	Imperfect	essem	starem		–	–	–	–	–	–	ser	estar	essere	istere	–	–	–	–	–	–
	Pluperfect	fuissem	stetissem		fossi	stessi	fusse	–	fuese	estuviese	fosse	estivesse	–	–	fos	estigués	fussi	stassi	fiss	fusesem
Infinitive		esse	stāre		essere	stare	être	–	ser	estar	ser	estar	essere	istare	ser, ésser	estar	siri	stari	esser	fire, a fi
Supine		–	statum		–	stato	–	été	sido	estado	sido	estado	essidu	istadu	estat, sigut, sét	estat	statu	statu	stà	fost
Gerund		–	standum		essendo	stando	–	étant	siendo	estando	sendo	estando	essende	istande	sent, essent	estant	sennu	stannu	essend, siond	fiind

• "To have": The verb habeō was regularly conjugated in Classical Latin, but later tends to be highly irregular in the Romance languages. The verb later transformed to *haveō in many Romance languages (but etymologically Spanish haber), resulting in irregular indicative present forms *ai, *as, and *at (all first-, second- and third-person singular), but ho, hai, ha in Italian and -pp- (appo) in Logudorese Sardinian in present tenses.

In Logudorese Sardinian, two -b-es lost in imperfect tenses.

In French, the past participle eu including the perfect stems (past historic and subjunctive imperfect stems) eu-/eû- rather evolved from earlier *habū-.

This is the Vulgar Latin conjugation of the verb *avére:

Vulgar Latin conjugation of *avére

Infinitive		*avére
Present participle		*avénte
Gerund		*avéndo
Supine		*áuto
		1st singular	2nd singular	3rd singular	1st plural	2nd plural	3rd plural
Indicative	Present	*áio	*áus	*áut	*avémos	*avétes	*áunt
	Imperfect	*avéba	*avébas	*avébat	*avébamos	*avébates	*avébant
	Preterite	*áui	*avésti	*áut	*avémos	*avéstes	*áuront
	Pluperfect	*avéra	*avéras	*avérat	*avéramos	*avérates	*avérant
	Future	*avére áio	*avére áus	*avére áut	*avére avémos	*avére avétes	*avére áunt
	Conditional	*avére avéba	*avére avéba	*avére avébat	*avére avébamos	*avére avébates	*avére avébant
	Future perfect	*avéro	*avéres	*avéret	*avéremos	*avéretes	*avérent
Subjunctive	Present	*áia	*áias	*áiat	*aiámos	*aiátes	*áiant
	Imperfect	*avére	*avéres	*avéret	*avéremos	*avéretes	*avérent
	Pluperfect	*avésse	*avésses	*avésset	*avessémos	*avessétes	*avéssent
Imperative			*áu			*avéte

Notice that these forms sometimes also have an inconsistent form, as the table above more resembling with that of French.

• "To do": The verb faciō is also irregular in Classical Latin, with fēc- before perfect tenses (although the passive form of the verb was supplied by fīō, this suppletion is not included as the passive voice became periphrastic). This verb is one of the few verbs that retains perfect ablaut in Romance languages, with some changing the perfect stem to fi- due to metaphony rules.

In spite of the remarkable continuity of form, several Latin tenses have changed meaning, especially subjunctives.

• The verbal noun became a present participle in all Romance languages except in Italian and Romanian, where it became a gerund, and Sardinian, where it does not exist. However, the French and Catalan suffixes -ant conflate with the accusative of present active participle suffix -āntem.
• The supine became a past participle in all Romance languages.
• The pluperfect indicative became a conditional in Sicilian, and an imperfect subjunctive in Spanish.
• The pluperfect subjunctive developed into an imperfect subjunctive in all languages except Romansh, where it became a conditional, and Romanian, where it became a pluperfect indicative.
• The future perfect indicative became a future subjunctive in Old Spanish, Portuguese, and Galician.

The Latin imperfect subjunctive underwent a change in syntactic status, becoming a personal infinitive in Portuguese and Galician.^[1] An alternative hypothesis traces the personal infinitive back to the Latin infinitive, not to a conjugated verb form.^[2]

In many cases, the empty cells in the tables above exist as distinct compound verbs in the modern languages. Thus, the main tense and mood distinctions in classical Latin are still made in most modern Romance languages, though some are now expressed through compound rather than simple verbs. Some examples, from Romanian:

• Perfect indicative: am fost, ai fost, a fost, am fost, ați fost, au fost;
• Future indicative: voi fi, vei fi, va fi, vom fi, veți fi, vor fi;
• Future perfect indicative: voi fi fost, vei fi fost, va fi fost, vom fi fost, veți fi fost, vor fi fost.

New forms also developed, such as the conditional, which in most Romance languages started out as a periphrasis, but later became a simple tense. In Romanian, the conditional is still periphrastic: aș fi, ai fi, ar fi, am fi, ați fi, ar fi.

• Romance languages
• Vulgar Latin

• Maurer, Theodoro H. (1968). O infinitivo flexionado português: estudo histórico-descritivo (in Portuguese). São Paulo: Companhia Editora Nacional.
• Paola Monachesi, The Verbal Complex in Romance: A Case Study in Grammatical Interfaces. Oxford: Oxford University Press, 2005.
• Osborne, Bruce (1982). "On the origin of the Portuguese inflected infinitive". In Anders Ahlqvist (ed.). Papers from the Fifth International Conference on Historical Linguistics, Galway, April 6–10, 1981. Amsterdam: John Benjamins Publishing Company. pp. 243–48. ISBN 978-90-272-3514-5.
• Williams, Edwin Bucher (1962). From Latin to Portuguese: Historical phonology and morphology of the Portuguese language (2nd ed.). Philadelphia: University of Pennsylvania Press.
• Wireback, Kenneth J. (1994). "The Origin of the Portuguese Inflected Infinitive". Hispania. 77 (3): 544–554. doi:10.2307/344992. JSTOR 344992.