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The mining of thin-coal seams as applied to the eastern coal-fields of Canada
Kellock Brown, J. F., (1917)
Coal resources of the Trinidad coal field in Huerfano and Las Animas Counties, Colorado
Johnson, Ross B., (1961)
The coal measures of the Philippines : a rapid history of the discovery of coal in the archipelago and subsequent developments, with the full text of the record of the MacLeod Coal Concession in Cebu, or the Uling-Lutac Coal and Railway Concesssion
Burritt, Charles H., (1901)