Mr. David Irving
Schlegelberger's undated (but definitely end-of-March 1942) minute on Lammer's reference to Hitler's ruling is in German Federal Archives (BA) file R.22/52. It was sent to Staatssekretär Freisler and two other officials (bottom left). This document has been published in facsimile in David Irving's books Hitler's War, Goebbels. Mastermind of the Third Reich, and Nuremberg, the Last Battle.