00273nam a2200109 a 450000500170000002000150001708200210003210000190005324500400007226000340011230000170014620251203090533.0  a0126565503  a630.274,bD, spe  aSpeeding C.R.W  aThe biology of agricultural systems  aLoNew DelhionbAcademicc1975  ax,262p, 22cm