Hansen, Chuck. U.S. Nuclear Weapons: The Secret History, Arlington, TX: Aerofax, 1988.
Hansen, Chuck. The Swords of Armageddon: U.S. nuclear weapons development since 1945, Sunnyvale, CA: Chukelea Publications, 1995 [1].
Smyth, Henry De Wolf. Atomic Energy for Military Purposes, Princeton University Press, 1945. (The first declassified report by the US government on nuclear weapons)