About “Hryggjarstykki”
Hryggjarstykki is a lost kings' saga written in Old Norse in the mid-twelfth century. The author was Eiríkr Oddsson, an Icelander about whom little is known. The work covers events involving Harald Gilli and his two sons, as well as Magnús the Blind and Sigurd Slembe, up to their deaths. Eiríkr wrote the saga based on accounts from Hákon Maw, a landed-man who was involved in the events, and other reliable sources who witnessed the actions. Some parts of the text were based on Eiríkr’s own observations. The saga is mentioned by Snorri Sturluson in Heimskringla, where its reliability is noted. (Summary adapted from Wikipedia, CC BY-SA 4.0.)
Some summaries adapted from Wikipedia, CC BY-SA 4.0.