International Symposium on the Biological Characterization of Human Tumours,8th,Athens,1979 International Symposium on the Classification of Brain Tumours International Symposium on the Origin and Distribution of the Elements International Symposium on Biological Control of Weeds International symposium on the chemistry of the coordination compounds International Symposium on the Chemistry of Cement International Symposium on the Extractive Metallurgy of Aluminum (Cologne)International Symposium on the Classification of Brain Tumours International Symposium on the Statistical Mechanics of Quarks and Hadrons International Symposium on the lmpact of Bioterchnology on Diagnostics