003780000a22001330004500020001500000060000800015082001600023100001500039245006400054260005100118260000900169300000800178650005800186  a8120409183  a100  a631.417 ORL  aOrlov, D S  aHumic substance of soils and general theory of humification  aNewdelhi, Oxford & IBH publishing co. pvt. ltd  c1995  a317  aSoil-humification/soil-general theory of humification