Paths to War Boyce & Robertson
Neville Chamberlain's Legacy Nicholas Milton
The Hollow Years [1930s France] Eugen Weber
Britain at War 1937-41 Daniel Todman
Munich [Fiction] Robert Harris
Step by Step Winston Churchill
Last Hope Island [Occupied Europe] Lynne Olson
Failure of a Mission Neville Henderson [British Ambassador Berlin 1937-40]
Journal 1935-44 [Romania] Mihail Sebastian
The Hitler Years 1933-39 Frank McDonough
Hitler Ian Kershaw
The Third Reich Michael Burleigh
There are many, many many books covering various aspects of the subject. The above is just a personal listing which I often turn to when lecturing on the topic,