@book{97500,
	author = {Symposium on Research into Agro-technical methods. Aiming at increasing the productivity of crops-co-efficients for the most efficient use of fertilizer nutrients and means for reducing the losses of nutrients to the environment under the condi},
	title = {Efficient use of fertilizers in agriculture; proceedings.},
	publisher = {Martinius Nijhoff},
	year = {1983},
	series = {Developments in Plant and soil sciences, vol.10},
	address = {Hague}
}