https://guides.loc.gov/finding-government-documents/declassified-documents https://guides.loc.gov/finding-government-documents/declassi... is an excellent sourc

https://guides.loc.gov/finding-government-documents/declassified-documents https://guides.loc.gov/finding-government-documents/declassi... is an excellent source. https://www.documentcloud.org/app?q=classified https://www.documentcloud.org/app?q=classified is also pretty interesting and has good search tools.