John Bell,

Speakable and Unspeakable in Quantum Mechanics , Cambridge University

Gregory Benford,

Timescape , Simon & Schuster, New York, 1980

Gregory Benford,

Cosm , Orbit, London, 1998

Ray Bradbury, 'A Sound of Thunder’, in

The Stories of Ray Bradbury , Knopf, New York, 1980

L. Sprague de Camp,

Lest Darkness Fall , Holt, New York, 1941

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