Author,Title,Edition,Publisher,Year,Series,Number,ISBN,ISSN,URL
"Coddington, Earl A. and Snoo, Hendrik Simon Victor de",Regular boundary value problems associated with pairs of ordinary differential expressions,,Springer-Verlag,1981,Lecture notes in mathematics,,"3540107061,0387107061",,https://cir.nii.ac.jp/crid/1130000793781249024