http://all-that-is-interesting.com/the-five-greatest-mysteries-of-human-history
http://www.viralnova.com/unsolved-earth-mysteries/
http://www.theoccultmuseum.com/9-chilling-unsolved-crimes-will-give-goosebumps/
https://the-line-up.com/creepy-unsolved-mysteries
https://en.wikipedia.org/wiki/Dyatlov_Pass_incident
https://en.wikipedia.org/wiki/Flannan_Isles_Lighthouse
http://www.express.co.uk/scotland/475203/Three-lighthouse-keepers-vanished-without-trace-on-Boxing-Day-1900-now-a-new-clue-could
https://en.wikipedia.org/wiki/Sodder_children_disappearance
https://en.wikipedia.org/wiki/Devil%27s_Footprints
http://www.historynet.com/mystery-of-the-ghost-blimp.htm
https://en.wikipedia.org/wiki/Who_put_Bella_in_the_Wych_Elm%3F
https://en.wikipedia.org/wiki/Salish_Sea_human_foot_discoveries
http://www.oddlyhistorical.com/2014/06/04/phantom-barber-pascagoula/
https://en.wikipedia.org/wiki/Lead_Masks_Case
http://www.ancient-origins.net/unexplained-phenomena/green-children-woolpit-12th-century-legend-visitors-another-world-002347