Implementation of a hilbert-r*tree in Erlang - https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDQQFjAA&url=http%3A%2F%2Fwww.cis.temple.edu%2F~vasilis%2FCourses%2FCIS750%2FPapers%2FHilbertRtree-Kamel.pdf&ei=8jrqUY21DuS9iwKvw4HoDQ&usg=AFQjCNEw_2CPlRBBGN-a82ZQojak4LBmaw&sig2=dc_GCJihwF9LbQ8sbz5j5A&bvm=bv.49478099,d.cGE