• Did the Vikings use crystal ‘sunstones’ to discover America? https://theconversation.com/did-the-vikings-use-crystal-sunstones-to-discover-america-53836 32 comments 12/2/2016

• Did the Vikings use crystal 'sunstones' to discover America? http://phys.org/news/2016-02-vikings-crystal-sunstones-america.html 3 comments 1/2/2016 history
• Did the Vikings use crystal ‘sunstones’ to discover America? https://theconversation.com/did-the-vikings-use-crystal-sunstones-to-discover-america-53836 3 comments 1/2/2016 history