Lindsey, Forrest. "Hitler's Bomb: Target: London and Moscow"
Divergence: 1941 CE
What if: Himmler consolidated the German atomic weapons program under the SS and provided all necessary resources to Heisenberg to construct A-bombs by 1944.
Summary: Atomic attacks on London and Moscow in early 1944 throw Allied war plans awry, but as no follow-up bombings ensue the Allies adapt to the new situation. The war ends in November as an atomic bomb is dropped on Berlin in conjunction with the (delayed) invasion of Normandy.
Published: In Third Reich Victorious: Alternate Decisions of World War II (ed. Peter G. Tsouras), q.v.