TITLE: References on Mathematics of the Vikings
QUESTION [8 upvotes]: I know maybe this question is more appropriate to the community History of Science and Mathematics, and I have already posted it there. But, since it is considerably smaller than the Mathematics community, it has reached very few people (around 49 views within almost one and a half day). Due to this, I think I can ask that question here, where I can reach more people and, then, increase the chances of getting satisfactory answers... (I didn't get any answer there and therefore I'll deleted the question, leaving it only here)
So, let's go to the question:
We know Vikings were good, among other things, in building ships, so they must have had some knowledge in astronomy, geography, maybe, math, and so on.
Is there any "good" reference (rather a book on the academic literature, which explores it in a more detailed and exhaustive way, instead of only "sites on the web") on the Mathematics of the Vikings? I need as much references on this subject as I can get... (I know this task can be difficult, and that such a reference MIGHT NOT EXIST, since Vikings could have had not a written culture, leaving no recording of the math they had possibly developed). 
Maybe a reference which is about Viking Science instead of Viking Math would help. 
Thank you!

REPLY [5 votes]: Viggo Brun, a Norwegian professor of mathematics, wrote a short book Regnekunsten i det gamle Norge (The Art of Calculating in Old Norway) in 1961. He gives examples from the Gulating Law and the Frostating Law involving calculations of fines, in particular when various relatives of killed persons were to be properly compensated. More distant relatives would get a fraction of the amount closer relatives were entitled to. The laws were codified in the 13th century, but are surely based on older traditions.