 Another important work is "De synodis", written early in 359 in preparation for the councils of Ariminium and Seleucia.Various writings comprise Hilary's 'historical' works.These include the "Liber II ad Constantium imperatorem", the "Liber in Constantium inperatorem", "Contra Arianos vel Auxentium Mediolanensem liber", and the various documents relating to the Arian controversy in "Fragmenta historica".