00309nam a2200109Ia 4500008004100000082002200041100002800063245003300091260004800124300001000172650001700182140113s9999    xx            000 0 und d  a631.459:631.61 G6  a" Ayres, Quincy Claude"  aSoil erosion and its control  b"New York : McGraw-hill book company, 1936"  a365p.  aSoil erosion