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2. Compaction of Agricultural Soils;Barnes;Am. Soc. Agric. Eng. Monogr.,1971
3. Sample preparation and stone content;Bascomb,1974
4. Towards the quantification of soil structure;Bullock;J. Micros.,1980
5. Tillage effects on root development, water uptake and growth of oats;Ehlers;Soil Tillage Res.,1980