Chemistry and Biology of Pteridines 1989 Pteridines and Folic Acid Derivatives : Proceedings of the International Symposium on Pteridines and Folic Acid Derivatives, Chemical, Biological and Clinical Aspects, Zurich, Switzerland, September 3-8, 1989 - Curtius, Hans Christoph 1923-2009; Ghisla, Sandro 1942-; Blau, Nenad 1946- (Walter de Gruyter, 1990)