David Nortion who has written The King James Bible: A Short History from Tyndale to Today wrote,
The Hebrew and Greek were often printed with other versions, notably Latin versions. These were of great use for translators, for Latin was the international vernacular of scholarship. The polyglots, the Complutensian and Plantin’s Antwerp polyglot (1569–72), included other ancient versions with sometimes interlinear Latin translations. Erasmus’s NT had his Latin translation, the Novum Instrumentum, in a parallel column.
Sanctes Pagninus’s extremely literal Latin translation, Veteris et Novi Testamenti nova translatio (1528), was highly influential, not just its literal Latin translation of the OT (other versions superseded its NT), but also because of its extensive use of rabbinic sources. Translators in several languages found their teacher in Pagninus. Coverdale was one such; the Bishops’ Bible translators were instructed to follow Pagninus and Münster ‘for the verity of the Hebrew’, and the KJB drew on Pagninus for some readings.6 Sebastian Münster had published an annotated Latin version of the OT, printed alongside the Hebrew in 1535 which also drew extensively on rabbinic sources. Though his translation did not have the enduring success of Pagninus’s, his annotations were long valued.
The Zurich Latin Bible of 1543 included a new translation of the Apocrypha, and a revised version of Erasmus’s Latin NT. The latest of these influential, annotated, Jewish-influenced Latin OTs was the work of Immanuel Tremellius and his son-in-law Franciscus Junius. It included translations of the OT, the Peshitta NT and the Apocrypha. The main new Latin version of the NT after Erasmus’s was Beza’s (1557); both included annotations and were frequently reprinted.
Presentation often enhanced the value of these versions, for they were usually presented as cribs. Ways of highlighting the connections between the Latin and the original languages were developed. The Complutensian Polyglot tied the words of the NT to the Vulgate by using superscript letters: the reader had only to glance from the Greek in the left column to the Latin in the right to see which word represented which.7 Interlinear texts were even easier to use. After the publication of Pagninus’s translation, 1528, few, perhaps none of the translators would have found themselves working from the original languages alone, aided by nothing more than grammars and dictionaries, and never would they have found themselves working without an already vast knowledge of the text in their heads: most knew the Vulgate intimately.
From the unknown first Hebrew writer to Beza, all these men contributed, directly or indirectly, to the KJB. Many more, especially continental vernacular translators such as Martin Luther and the makers of dictionaries, grammars and concordances, should be added, but this is sufficient to give a sense of the books the English translators worked from.