Coba jelasin Ibn al-Athir dari Frederick I, Maharaja Suci Rom dalam bahasa melayu dong

Romuald of Salerno. Chronicon in Rerum Italicarum scriptores.

The "Bergamo Master". Carmen de gestis Frederici I imperatoris in Lombardia.

Chronicon Vincentii Canonici Pragensis in Monumenta historica Boemiae by Fr. Gelasius Dobner (1764)

MSN Encarta – Frederick I (Empayar Suci Rom)(  2009-10-31)

Famous Men of the Middle Ages – Frederick Barbarossa

Charter given by Emperor Frederick for the bishopric of Bamberg showing the Emperor's seal, 6.4.1157 . Taken from the collections of the Lichtbildarchiv älterer Originalurkunden at Marburg University