Biological activity and chemical structure : proceedings of the IUPAC-IUPHAR symposium held in Noordwijkerhout (The Netherlands), August 30-September 2, 1977 / ed. by J.A. Keverling BuismanStrategy in drug research : proceedings of the second IUPAC-IUPHAR Symposium held in Noordwijkerhout (The Netherlands), August 25-28, 1981 / ed. by J.A. Keverling Buisman ; [pref. by H. Timmerman]