Which preposition to use with schrader

in Occurrences 1%

II, p. 60, and Prof. Schrader in his "Hollenfahrt der Istar," pp. 90-95.

to Occurrences 1%

Miss Wiggin tells us that indirectly we owe the children's sand-heaps in the public parks to Froebel, since these were the result of a suggestion made by Frau Schrader to the Empress Frederick, and the idea was carried out during her husband's too brief reign.

Which preposition to use with  schrader