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 The NPS Scenario Authoring and Visualization for Advanced Graphical Environments
 (SAVAGE) Research Group maintains a large archive of dynamic 3D military models
-and open-source authoring tools, all built using Extensible 3D (X3D) graphics.
+and open-source authoring tools, all built using [Extensible 3D (X3D)](http://www.web3d.org/x3d/what-x3d) graphics.
 
 Archive support includes X3D-Edit authoring tool, X3D Tooltips, X3D Validator,
 complete course slidesets and videos, plus this open-source model archive.