His work has suffered substantially from manuscript transmission. Aside from the loss of the first thirteen books, the remaining eighteen are in many places corrupt and lacunose. The sole surviving manuscript from which almost every other is derived is a ninth-century Carolingian text, Vatican lat. 1873 ("V"), produced in Fulda from an insular exemplar. The only independent textual source for Ammianus lies in Fragmenta Marbugensia ("M"), another ninth-century Frankish codex which was taken apart to provide covers for account-books during the fifteenth century. Only six leaves of "M" survive; however, before this manuscript was dismantled the Abbot of Hersfeld lent the manuscript to Sigismund Gelenius, who used it in preparing the text of the second Froben edition ("G"). The dates and relationship of V and M were long disputed until 1936 when R. P. Robinson demonstrated persuasively that V was copied from M. As L. D. Reynolds summarizes, "M is thus a fragment of the archetype; symptoms of an insular pre-archetype are evident."