Identifies Burns's "English" source that he put into "Scots dress'"for the song 'It is na, Jean, thy bonie face." first published in James Johnson's Scots Musical Museum, IV (1792); reviews the evidence that Burns had read the source identified, in Juvenile Poems (1789), by John Armstrong (1771-1797), then a student at Edinburgh University; and explores why Davidson Cook's previous record of this identification, in 1918, has been lost to subsequent Burns scholarship. [in the original article, which was linked at http://burnsc21.glasgow.ac.uk/guest-blog-by-professor-patrick-scott-a-burns-puzzle-solved-davidson-cook-and-the-english-original-for-it-is-na-jean-thy-bonie-face-smm-333/, a brief afterword by Murray Pittock put the (re)discovery in the context of other current work on Burns attribution.] The original posting seems to have disappeared from the Glasgow project site. The copy attached here is a slightly revised version as published in Burns Chronicle, 126 (2017), 42-46.