1. Asymptotic expansions for ordinary differential equations;Wasow,1966
2. The central connection problem at turning points of linear differential equations;Wasow;Communs Math. Helv.,1971
3. On full uniform simplification of even order linear differential equations with a parameter;Kohno;Hiroshima Math. J.,1979
4. Asymptotic laws of distribution of eigenvalues for some singular types of second-order differential equations;Dorodnitsyn;Usp. Mat.,1952
5. General connection formulae for Liouville-Green approximation in the complex plane;Olver;Philos. Trans. Roy. Soc., London,1978