John W. Baldwin, "Master Stephen Langton, Future Archbishop of Canterbury: The Paris Schools and Magna Carta", The English Historical Review, Volume CXXIII, Issue 503, 1 August 2008, Pages 811–846, saying, "As a postscript to Stephen Langton's role in Magna Carta, some detective work is required to account for the Unknown Charter at Paris. Initially found in the French archives by an English Royal Commission early in the nineteenth century, it lay buried in their unpublished reports. The French archivist Alexandre Teulet had edited it in 1863 in his comprehensive Layettes du Trésor des Chartes (vol. I, nos. 34 and 1053), but it was John Horace Round who ‘discovered' it thirty years later in 1893 as he was examining the reports of the Royal Commission in London."
