LIGNITE AND BROWN COAL (PETROGRAPHY)
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BTCARBONIFEROUS ROCKS (PETROGRAPHY)
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UDC552.576
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Descriptor GERLIGNIT UND BRAUNKOHLE (PETROGRAPHIE)
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Descriptor ENGLIGNITE AND BROWN COAL (PETROGRAPHY)
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Descriptor FRELIGNITE ET HOUILLE BRUNE (PÉTROGRAPHIE)
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NTBROWN COAL (PETROGRAPHY)
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NTLIGNITE, TRUE LIGNITE (PETROGRAPHY)