002890000a22001210004500060000800000082001500008100001700023245003500040260003500075260000900110300000800119650004000127  a100  a631.47 CLA  aClarke,  G R  aStudy of the soil in the field  aAt the clarendon press, Oxford  c1936  a204  aSoil samplilng/ Soil survey-Mapping