Pope Martin IV
Duchesne attributes all biographies from Pope Gregory VII to Urban II to Pandulf, while earlier historians like Giesebrecht and Watterich attributed the biographies of Gregory VII, Victor III, and Urban II to 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.