Harry S Truman Presidential Library and Museum trumanlibrary.org/
Comprehensive collections of primary documents released through the Freedom of Information Act. Includes many aspects of U.S. foreign policy and military policy from 1945 to the present. Overlaps with U.S. Declassified Documents but has more recent documents.
Mugar JX 233 E52
see esp. (Truman) FOREIGN RELATIONS OF THE UNITED STATES: DIPLOMATIC PAPERS, 1945, GENERAL: POLITICAL AND ECONOMIC MATTERS, VOLUME II
J. Robert Oppenheimer Personnel Hearings Transcripts
In December 1953, the Atomic Energy Commission (AEC) suspended the security clearance of Dr. J. Robert Oppenheimer, and after a four-week, closed-door hearing in April and May 1954, formally revoked that clearance. In June 1954, the AEC released a redacted version of the hearing transcript, (see AEC press release), with security classified information deleted. Sixty years later, the Department of Energy has re-reviewed the original transcript and is making available to the public, for the first time, the full text of the transcript in its original form.
https://nsarchive2.gwu.edu/NSAEBB/NSAEBB162/5.pdf