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41
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42
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43
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44
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45
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46
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47
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48by Wright, Charles H“...[U. S. Dept. of the Interior, Office of Coal Research]; for sale by the Supt. of Docs. U. S. Govt...”
Published 1973
Book -
49by Given, P. H (Peter Hervey), 1918-1988“...U. S. Dept. of the Interior, Office of Coal Research; for sale by the Supt. of Docs., U. S. Gov...”
Published 1973
Book -
50
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51
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52
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53
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54by Armbruster, Frank E“...U.S. Dept. of the Interior, Office of Coal Research ; for sale by the Supt. of Docs., U.S. Govt...”
Published 1974
Government Document Book