Ordinary and Partial Differential Equations : Proceedings of the Sixth Conference Held at Dundee Scotland March 31 – April 4 1980 Equivalence of differential operators Some unitarily equivalent differential operators with finite and infinite singularities The land beyond bessel: A survey of higher special functions Nonlinear two point boundary value problems On nonlinear boundary value problems for an elliptic system in the plane Totally singular extensions of the Cauchy problem for a special class of partial derivative operators with distributional coefficients Complex extensions of a submanifold of solutions of the sine gordon equation Remark on bifurcation problems with several parameters Asymptotic theory and deficiency indices for fourth and higher order self adjoint equations: A simplified approach On the spectra of Schrödinger operators with a complex potential Non modal eigenfunction expansions Asymptotic distribution of eigenvalues of elliptic operators on unbounded domains Generalized hyperanalytic function theory Some spectral gap results A regular left definite eigenvalue problem with eigenvalue parameter in the boundary conditions Some topics in nonlinear wave propagation An ordering of oscillation types for y(n) + py = 0 Fundamental properties of the solutions of quasilinear differential equations of the fifth order Oscillation properties of weakly nonlinear differential equations On boundary integral equation methods in stationary electromagnetic reflection Norm inequalities for derivatives Fixed point theorems Automatic control of errors for invariant imbedding A bound for solutions of a fourth order dynamical system Reducibility of almost periodic linear systems Convergence of solutions of infinite delay differential equations with an underlying space of continuous functions On a system of non linear strongly coupled partial differential equations arising in biology Differential operators with discrete spectrum On spectral theory for the linear selfadjoint equation Fy = Gy Estimates for some free boundary problems A new proof of existence of similarity solutions Symmetry and bifurcation from multiple eigenvalues Convergence to a travelling wave in an initial boundary value problem Geometric remarks on second order criteria for maxima and minima Variational methods and almost solvability of semilinear equations.