org/licenses/by-sa/4.0CC BY-SA 4.0 Creative Commons Attribution-Share Alike 4.0 truetrue English Letter by Wilfred G. Lambert describing 4 sided spinning top...
org/licenses/by-sa/4.0CC BY-SA 4.0 Creative Commons Attribution-Share Alike 4.0 truetrue English Ancient 4 sided spinning top determination method:...