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Ficheiro:Formation periods of the most important coal deposits worldwide.svg

file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. Attribution: Bartz/Stockmar - Coal Atlas, 2015 You are free:...

Ficheiro:Coal Atlas.pdf

file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. Attribution: Bartz/Stockmar - Coal Atlas, 2015 You are free:...

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