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Federal Bureau of Investigation (FBI)

Courtesy of the Harvard University Archives (Harvard)

Herblock © 1950 The Washington Post Co., from Herblock’s Here and Now (Simon & Schuster, 1955) (Herblock)

Inga Hiilivirta (Hiilivirta)

J. Robert Oppenheimer Memorial Committee Photographs (JROMC)

Yousuf Karsh/Retna Ltd. (Karsh)

Lawrence Berkeley National Lab (Berkeley)

Los Alamos National Laboratory Archives (LANL)

Anne Wilson Marks (Marks)

National Academy of Sciences (NAS)

National Archives (NA)

Niels Bohr Archive, courtesy AIP Emilio Segre Visual Archives (Bohr)

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Alan W. Richards, Princeton, N.J., courtesy AIP Emilio Segre Visual Archives (Richards)

Barbara Sonnenberg (Sonnenberg)

Ulli Steltzer (Steltzer)

Dr. Hugh Tatlock (Tatlock)

Time & Life Pictures/Getty Images (Getty)

United Press International, courtesy AIP Emilio Segre Visual Archives, Physics Today Collection (UPI)