* [https://www.google.com/maps/views/streetview/oceans?gl=us Google Street View of the Great Barrier Reef]
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* [https://www.google.com/maps/views/view/streetview/oceans/st-crispins-reef-great-barrier-reef/xXFiD1jApxEAAAQfCaZacg?gl=us&heading=65&pitch=107&fovy=75 Google Street View of the Great Barrier Reef]
* [http://en.wikibooks.org/wiki/Historical_Geology/Reefs Good definition of reefs in a geologic rather than nautical sense]
* [http://en.wikibooks.org/wiki/Historical_Geology/Reefs Good definition of reefs in a geologic rather than nautical sense]
* [http://www.sunstar-solutions.com/sunstar/geology/Permian/PermianTX.htm Permian reefs in west Texas, USA]
* [http://www.sunstar-solutions.com/sunstar/geology/Permian/PermianTX.htm Permian reefs in west Texas, USA]