The “boke of children” is the first work on diseases of children to be written by an Englishman the English language. Phaer enabled Englishmen to read and think of pediatrics in their own language. The edition included Phaer's translation of Jehan Goeurot's The regiment of lyfe, a translation of the Regimen of Salerno, and Phaer's A goodly bryefe treatise of the Pestylence, a treatise on the plague.
See Thomas Phaer and the boke of chyldren (1544) edited by Rick Bowers. Tempe, AZ: Arizona Center for Medieval and Reniassance Studies, 1999. Digital facsimile of the 1999 edition from the Internet Archive at this link.
Reprint of 1553 edition, edited by A.V. Neale and H.R.E. Wallis, Edinburgh, 1955. Also reprinted in Rühräh (No. 6354).