00282nam a2200097Ia 4500008004100000082001600041100004500057245004100102260003300143300000800176140113s9999    xx            000 0 und d  a63:574   M1  a"Spedding, C.R.W., Walsingham and Hoxey"  aBiological efficiency In agriculture  a1981bAcademic PresscLondon  a383