Asymptotic theory and deficiency indices for fourth and higher order self-adjoint equations: A simplified approach. (English) Zbl 0514.34047

Ordinary and partial differential equations, Proc. 6th Conf. Dundee 1980, Lect. Notes Math. 846, 88-99 (1981).


34E05 Asymptotic expansions of solutions to ordinary differential equations
34C20 Transformation and reduction of ordinary differential equations and systems, normal forms