Agawa, Hiroyuki; Bester, John (trans.), The Reluctant Admiral (Kodansha, 1979), ISBN 4-7700-2539-4. The definitive biography of Yamamoto in English. This book explains much of the political structure and events within Japan that lead to the war, with many details unfamiliar to most Americans.
Hoyt, Edwin P., Yamamoto: The Man Who Planned Pearl Harbor (McGraw-Hill, 1990), ISBN 1-58574-428-X.
Fading Victory: The Diary of Admiral Matome Ugaki, 1941-45. University of Pittsburgh Press, Copyright 1991. ISBN 0-8229-5462-1. A high-level view of the war from the Japanese side is within the diaries of Yamamoto's Chief of Staff, Admiral Matome Ugaki. Here will be found evidence of the intentions of the imperial military establishment to seize Hawaii and to operate in the Indian Ocean. Translated by Masataka Chihaya, this edition contains extensive clarifying notes from the U. S. editors derived from the U. S. military histories.
