http://www.mnn.com/lifestyle/arts-culture/stories/15-famous-people-who-mysteriously-disappeared
http://listverse.com/2007/10/06/top-10-bizarre-disappearances/
http://www.listosaur.com/bizarre-stuff/5-strange-mass-disappearances-in-history/
http://www.toptenz.net/top-10-unexplained-disappearances.php
http://listverse.com/2013/04/13/10-mysterious-disappearances-of-multiple-people/
http://www.toptenz.net/top-10-most-mysterious-disappearances-in-history.php
http://www.mnn.com/green-tech/research-innovations/blogs/nazca-mystery-solved-no-trees-no-civilization