The Path to War in 1939: A Very Partial and Personal Booklist

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,