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2. Some investigations into the bearing capacities of floor in the Northumberland and Durham Coalfields;Jenkins;Trans. Instn Min. Engrs,1958
3. In situ tests on bearing capacity of roof and floor in selected bituminous coal mines;Barry;U.S.B.M. Report No. 4706,1970
4. Testing mine floors;Lee;Colliery Engng,1961
5. Underclays of South Wales coalfield and their influence on floor penetration;Platt,1957