Tolong jelaskan mengenai Catatan dari Bertha dari Savoia

Bruno of Merseburg, Brunonis Saxonicum bellum in Brunos Buch vom Saxonkrieg, ed. H-E. Lohmann, MGH Dt. MA 2 (Leipzig, 1937), accessible online at: Monumenta Germaniae Historica  (in Latin)

Bruno of Merseburg, Brunonis Saxonicum bellum. Brunos Sachsenkrieg, in Quellen zur Geschichte Kaiser Heinrichs IV., ed. and trans. F-J. Schmale (Darmstadt, 1968), pp. 191–405. (in German)

Lampert of Hersfeld, Annales, in Lamperti monachi Herfeldensis Opera, ed. O Holder-Egger, MGH SS rer Germ 38 (Hannover and Leipzig, 1894), accessible online at: Moumenta Germaniae Historica  (in Latin)

I.S. Robinson, Henry IV of Germany, 1056-1106 (Cambridge, 2003).