1. Second order linear ordinary differential equations with turning points and singularities I, II;Nakano,1977
2. Second order linear ordinary differential equations with turning points and singularities I, II;Nakano;Kodai Math. J.,1978
3. Reduction of the order of a linear ordinary differential equation containing a small parameter;Iwano,1963
4. On a system of linear ordinary differential equations with a turning point;Nakno,1969
5. On matching method for a linear ordinary differential equation containing a parameter I;Nishimoto,1965