International Conference on Spectral Theory of Differential Operators,Birmingham,1981 International Conference on Recent Adances in Differential Equations International conference on the strength of metals & alloys International Conference on Differential Equations Speictral theory of differential operators International Conference on the Physics of Semiconductors International Conference on the Physics of Semicorductors International Conference on the Theory and Applications of Graphs Selected papers on general partial differential operators Selecton Papers on General Partial Differential Operators