Vertraulicher Briefwechsel mit Sigmund Pruschenk, edited by V.
528-623; Sigmund Riezler, Die literarischen Widersacher der Piipste zur Zeit Ludwig des Baiers (Leipzig, 1874).
The system of the quadratic and cubic, consisting of 15 forms, and that of two cubics, consisting of 26 forms, were obtained by Salmon and Clebsch; that of the cubic and quartic we owe to Sigmund Gundelfinger (Programm Stuttgart, 186 9, 1 -43); that of the quadratic and quintic to Winter (Programm Darmstadt, 1880); that of the quadratic and sextic to von Gall (Programm Lemgo, 3873); that of two quartics to Gordan (Math.
At Halle he was influenced, especially in philosophy, by Sigmund J.
Brandenburg, Keinig Sigmund and Kurfurst Friedrich I.