OC 52/36 Typewritten letter from Hertzka (UE) to Schenker, dated March 29, 1909

Hertzka welcomes the prospect of a discussion at the home of Robert Brüunauer.

OC 52/402 Typewritten letter from Hertzka (UE) to Schenker, dated March 21, 1909

Hertzka raises several possibilities for amplifying the Instrumentations-Tabelle, and calls for a meeting.

WSLB 37 Handwritten letter from Schenker to Hertzka (UE), March 28, 1909

Schenker suggests a meeting at Robert Brünauer's home.

Diary entry by Schenker for 7 March 1909

Diary entry by Schenker for 8 March 1909

Diary entry by Schenker for 21 March 1909