sponsored by the Commission of the European Communities, Directorate-General for Agriculture and Directorate-General for Research, Science, and Education ; edited by P. L'Hermite and J. Dehandtschutter
organized jointly by the CEC and the Institute for Soil Fertility, Haren (Gr.), and held in Groningen, Netherlands, on June 12 and 13, 1980 ; sponsored by the Commission of the European Communities, Directorate-General for Agriculture, and Directorate-General for Research, Science and Education ; edited by T.W.G. Hucker and G. Catroux