Generally considered the comprehensive history regarding the decision to use nuclear weapons against Japan. Alperovitz's book is long and dense tome that covers as much of the debate around the issue as a historian can. Most of our narrative regarding this topic are taken from this book.
If you don't want to read a 900 page book, Alperovitz gave a lecture in 1994 as he was finishing his book that lays out his basic thesis. A free transcript of that talk can be found here.
Charles Lindbergh, who served as a civilian observer and pilot in New Guinea in 1943, wrote of the US treatment of Japanese POWs in his diary: "It was freely admitted that some of our soldiers tortured Jap prisoners and were as cruel and barbaric at times as the Japs themselves. Our men think nothing of shooting a Japanese prisoner or a soldier attempting to surrender. They treat the Japs with less respect than they would give to an animal, and these acts are condoned by almost everyone." Quoted in John Dower, War Without Mercy: Race & Power in the Pacific War (1986)
Kurt Wittfogel's 1957 book, Oriental Despotism, provided the academic cover for the transition from antisemitic attacks on the Soviet Union in the West to an Orientalist approach – a transition required as the facts of the Holocaust came to light in the West forcing a pivot away from the Jewish conspiracy line promoted in the 1920s and 30s. Now that such blatantly orientalist approaches are no longer considered socially acceptable, Western academics have decided that the Soviet Union is actually a "white settler-colonial" state. From Jewish conspiracy to Asiatic despotism to white settler colonial state, the historical dissonance never seems to bother Western academics.