Presidential messages to Congress
Executive Agencies' reports to Congress
Committee sponsored special studies
Senate Treaty Documents
GovInfo - Select committee documents, the earliest are from 1975 (94th Congress).
Bloomberg Law - selected pdf committee documents from 1995
Proquest Congressional - committee documents from 1819 to 1989
Proquest Legislative Insight - committee documents associated with enacted legislation from 1929 forward.
The Library has the full text of House and Senate documents in microfiche, dating back to 1915. Contact a reference librarian at askthelibrary@brooklaw.edu for help.