003510000a22001210004500060000800000082002300008100001500031245007100046260005500117260000900172300000800181650004000189  a100  a589.460 413 35 SIN  aSingh, R N  aRole of blue green algae in nitrogen economy of Indian agriculture  aNew Delhi, Indian Council of Agricultural Research  c1961  a175  aSoil algae/ Biological productivity