‎"KOCH, HELGE VON.‎
‎Sur une application des déterminants infinis à la théorie des équations différentielles linéaires (+) Sur les déterminants infinis et les équations différentielles linéaires.‎

‎[Berlin, Stockholm, Paris, Beijer, 1891 - 1892]. 4to. Without wrappers as extracted from ""Acta Mathematica. Hrdg. von G. Mittag-Leffler."", Bd. 15 and 16. Fine and clean. Pp. 53-63" Pp. 217-295.‎

Reference : 45853

‎First printing of Koch's two paper which together constitute his doctoral thesis. Von Koch is known principally for his work in the theory of infinitely many linear equations and the study of the matrices derived from such infinite systems. He also did work in differential equations and in the theory of numbers. (DSB).‎