36 CFR § 1256.22
How do I request access to restricted information in Federal archival records?
November 4, 2020
(a) You may file a FOIA request. To request access under the provisions of the FOIA, see part 1250 of this chapter, Public Availability and Use of Federal Records.
(b) For classified information in Federal records, you may file a FOIA request or a mandatory review request under Executive Order 12958, as amended, as described in §1256.74.