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 ## Related References
 
-d. [Extensible 3D (X3D) Graphics](https://www.web3d.org/x3d/what-x3d) is the international standard for publishing interactive 3D models on the Web.
+d. 3D models used in SPIDERS3D are produced from a variety of sources, then converted (if necessary) to X3D for mashup composition and Web-based collaborative visualization.  [Extensible 3D (X3D) Graphics](https://www.web3d.org/x3d/what-x3d) is the international standard for publishing interactive 3D models on the Web.
 
 e. [Web3D Consortium](https://www.web3d.org) is an international, non-profit, member-funded, industry Standards Development Organization (SDO) founded in 1997. Web3D working groups and community develop X3D capabilities, now at [X3D version 4](https://www.web3d.org/x3d4).