This applet makes use of the excellent d3js javascript library.
Please see the GitHub site for details about licensing of other libraries that may have been used in the source code for this applet.
Licence
Creative Commons Attribution 4.0 International.
License (CC BY 4.0). To view a copy of this license, visit
http://creativecommons.org/licenses/by/4.0/ or send a letter to Creative Commons, 559
Nathan Abbott Way, Stanford, California 94305, USA.