according to the account of the wise and discriminating man Eiríkr Oddsson. The tale is mostly from the report of the district chieftain Hákon magi, who presided and told of these events when they were first written down. He himself and his sons participated in these expeditions and most of the battles. He knew the men who are named here. He who wrote the story also named several truthful men as sources for the account.

The author of Fagrskinna also made use of Hryggjarstykki though he did not explicitly