U.S. Government Resources
The U.S. Government is the world's largest publisher and has produced significant quantities of information on German History during this time period. A good index to begin with is Monthly Catalog of United States Government Publications HSSE Periodicals 016.353 Un36 and online from 1976-present with many recent documents being freely available in full text.
CIS Index to U.S. Congressional Committee Hearings 1833-1969 HSSE REF 348.731 C76
CIS U.S. Congressional Committee Hearings Index (1970-present) HSSE REF & Periodicals 328.73005 C76
Digital United States Congressional Serial Set (Purdue Users Only) (Resource providing access to U.S. Government documents, including congressional committee legislative reports, from 1789-1969).
U.S. Declassified Documents Online (Purdue Users Only!)
Foreign Relations of the United States HSSE Periodicals 327.73 Un32 and also online here (Official U.S. foreign policy documentary record.) The State Dept. Historians Office has additional resources you can use.
Central Intelligence Agency Freedom of Information Act (Features numerous declassified CIA national intelligence estimates on various countries. Select "Special Collections" then "National Intelligence Council" before beginning your search.)
Soviet and Warsaw Pact Military Journals from CIA 1961-1986)
Information Bulletin (HIKS Repository W 1.72/8 & S 1.85 (Newspaper produced by U.S. military authorities in charge of occupying Western Germany after World War II.)
National Archives Access to Archival Database (The full text of many State Department Central File records are accessible here from 1973-1979.)
National Security Agency Historical Publications (Document NSA cryptologic history)
National Security Archive Electronic Briefing Books (This George Washington University project compiles declassified U.S. Government documents on foreign and national security policy.)
Selected full text State Dept. Documents from the Hathitrust catalog.
Trials of the Major War Criminals Before the International Military Tribunal (Nuremberg Trials)HSSE 341.3 In85
U.S. Strategic Bombing Survey Reports (European War) HIKS Repository W 1.71 (U.S. military reports measuring and assessing the impact of allied bombing during World War II.: Selected holdings.)