00386nam a2200097Ia 4500008004100000082002600041100003500067245013800102260004000240300000800280140113s9999    xx            000 0 und d  a631.811.3:581.19   L1  aInternational Potash Institute  aTransition from extensive to intensive agriculture with fertilizers :Proceedings of the 7th Colloquium International Potash Institute  a1969bPotash InstitutecSwitzerland  a282