ABBREVIATIONS USED IN
NOTES AND BIBLIOGRAPHY
| BI | United States Bureau of Investigation (now FBI) |
| BT | Board of Trade |
| CAB | Cabinet (UK) |
| CCAC | Churchill College Archives Centre |
| FSB | Federalnaya Sluzhba Bezopasnosti (Federal Security Service) |
| FO | Foreign Office |
| GPU | Gosudarstvennoye Politicheskoye Upravleniye (State Political Directorate) |
| HO | Home Office |
| MID | Military Intelligence Division (US) |
| MI1c | Military Intelligence 1c (see SIS) |
| MI5 | Military Intelligence 5 – the Security Service |
| NID | Naval Intelligence Department/Division (UK) |
| OGPU | Obyedinennoye Gosudarstvennoye Politicheskoye Upravleniye (Unified State Political Directorate) |
| ONI | Office of Naval Intelligence (US) |
| PRO | Public Record Office, Kew (now National Archives) |
| SIS | Secret Intelligence Service (MI1c, now MI6) |
| WO | War Office |