 The "Annals of the Four Masters" are late, and include some material of doubtful origin.While the annals provide a considerable amount of information, they are generally terse, and most focus their attention on the doings of the Uí Néill, sometimes to the extent of omitting inconvenient events.A source which concentrates on Cerball's career is the "Fragmentary Annals of Ireland", so called because only fragments remain of a seemingly longer work, these again copied by Mac Fhirbhisigh in the 17th century from a 15th-century manuscript.