Yang Xi
Although no autograph copies of Yang Xi's famous calligraphy have survived, one well-documented stone rubbing version of the revealed "Huangting jing" (黃庭經, Yellow Court Scripture) has been given special attention. The Song dynasty connoisseur and critic Mi Fu (1051-1107) analyzed four manuscripts of the "Huangting jing", and said the best one was written on a silk scroll with a provenance that he traced back to the early 8th century. Mi disagreed with a former owner Tao Gu (陶穀, 903-970) who said that Wang Xizhi wrote the manuscript, and concluded it was a superb example of calligraphy from the Six Dynasties period. The Ming dynasty calligrapher and painter Dong Qichang (1555-1636) was so impressed by the Mi Fu manuscript that he made a copy, recommend it as the best model for studying "kaishu" script, and included it as the first example in his classic "Xihong tang fatie" (戲鴻堂法帖, Calligraphy Compendium of the Hall of the Playful Goose). Dong's colophon attributed the calligraphy to Yang Xi himself and described it as "the traces of a holy immortal" (Ledderose 1984: 262-263, who calls Dong's attribution to Yang "extremely optimistic").
History of the Lombards
The relations between these manuscripts were studied by Georg Waitz, who in 1876 identified 11 different families of the "Historia Langobardorum". The oldest manuscript is the Palimpsest of Assisi, written in the uncial script towards the end of the 8th century, almost immediately after Paul's work was completed. This palimpsest is, however, far from complete, as it contains only parts of books II and V of Paul's history. The earliest complete manuscript is the "Codex Sangallensis 635" written sometime between the 8th and the 10th centuries and designated by Waitz as F1. According to Waitz, F1's age makes it the most reliable of the "Historia"'s codices, a view which has been challenged by Antonio Zanella and Dante Bianchi, both of whom hold that the F1 does not correctly reflect Paul's original. 
Paul's account was largely accepted by subsequent writers, was often continued, and was first printed in Paris in 1514. Among the printed editions of the Latin text, the most authoritative is that edited by Ludwig Konrad Bethmann and Georg Waitz and published in the "Monumenta Germaniae Historica. Scriptores rerum langobardicarum et Italicarum" (Hanover, 1878).