Editing Liber Pontificalis (section)

===Petrus Guillermi===
Duchesne refers to the 12th-century work by [[Petrus Guillermi]] in 1142 at the [[monastery of St. Gilles]] ([[Diocese of Reims]]) as the ''Liber Pontificalis of Petrus Guillermi (son of William)''.<ref name="catholic"/> Guillermi's version is mostly copied from other works with small additions or excisions from the papal biographies of Pandulf, nephew of [[Hugo of Alatri]], which in turn was copied almost verbatim from the original ''Liber Pontificalis'' (with the notable exception of the biography of [[Pope Leo IX]]), then from other sources until [[Pope Honorius II]] (1124–1130), and with contemporary information from [[Pope Paschal II]] (1099–1118) to [[Pope Urban II]] (1088–1099).<ref name="catholic"/>

Duchesne attributes all biographies from [[Pope Gregory VII]] to Urban II to [[Pandolfo da Lucca|Pandulf]],<ref name="catholic"/> while earlier historians like [[Giesebrecht]]<ref>"Allgemeine Monatsschrift", Halle, 1852, 260 sqq.</ref> and [[Watterich]]<ref>Romanorum Pontificum vitæ, I, LXVIII sqq.</ref> attributed the biographies of Gregory VII, Victor III, and Urban II to [[Cardinal Petrus Pisanus|Petrus Pisanus]], and the subsequent biographies to Pandulf. These biographies until those of [[Pope Martin IV]] (1281–1285) are extant only as revised by Petrus Guillermi in the manuscripts of the monastery of St. Gilles having been taken from the Chronicle of [[Martin of Opava]].<ref name="catholic"/>

Early in the 14th century, an unknown author built upon the continuation of Petrus Guillermi, adding the biographies of popes [[Pope Martin IV|Martin IV]] (d. 1285) through [[Pope John XXII|John XXII]] (1316–1334), with information taken from the "[[Chronicon Pontificum]]" of [[Bernard Gui|Bernardus Guidonis]], stopping abruptly in 1328.<ref name="catholic"/>