Nicephorus Gregoras
Kantakouzenos retired to a monastery, where he assumed the name of Joasaph Christodoulos and occupied himself with literary labors, which have been called eloquent. His 4-volume "History" of the years 1320-1356 served as an apologia for his actions. They are therefore not always trustworthy, including defects in matters where he was not personally involved, but are supplemented by the contemporary work of Nicephorus Gregoras. It is nevertheless remarkable for being the only surviving account any Byzantine emperor gave of his own reign.