Wolf, Kenneth Baxter. The deeds of Count Roger of Calabria and Sicily and of his brother Duke Robert Guiscard. University of Michigan Press. 2005. Robinson
[2018-02-07]. (原始内容存档于2018-09-23) (英语). The Deeds of Count Roger of Calabria & Sicily & of Duke Robert Guiscard his brother, Geoffery Malaterra. Translated by Graham