Frischauer, Himmler; also Wenzel Jaksch, Europe's Road to Potsdam (London and New York, 1964) and Wighton, Heydric. See also Hitler's remark noted by Goebbels in his Diaries that Heydrich's policy in the Protectorate was 'truly a model one' (entry for 21st January 1942). on such remarks by Hitler, Himmler commented to his masseur, Felix Kersten:
'Heydrich was one of the few men who knew the right way to treat a foreign nation. If he had trampled on the Czechs with hobnailed boots, the English secret service would have kept a careful watch to see that nothing happened to him'. (Memoirs)
On Heydrich's policy see also The Goebbels Diaries, entry for 15th February 1942.