Тагнуул

Тагнуул гэдэг нь тусгай зорилгоор ямар нэгэн юмыг нууц аргаар мэдэх, мэдээлэх явдал юм. Я.Цэвэл. Монгол хэлний товч тайлбар толь. УБ, 1966, 514-р тал 

Тайлбар
Тагнуулын үйл ажиллагааны талаар дэлхийн улс орнуудад хүлээн зөвшөөрөгдсөн нийтлэг тодорхойлолт байхгүй.   Судлаачид тагнуулын үйл ажиллагааг “Улс төрчид, цэргийн удирдагчид чухал асуудлаар шийдвэр гаргахдаа ашигладаг мэдлэг, урьдчилан харсан мэдээлэл”, эсвэл  гадаад бодлого боловсруулах, стратегийн шийдвэр гаргахад улс орныхоо удирдлагад шаардлагатай мэдээллүүдийг нууц, ил эх сурвалжуудаас цуглуулах, дүн шинжилгээ хийх, үнэлэх, ангилан боловсруулах зэргийг багтаасан, засгийн газрын агентлагуудаас үндсэндээ нууцаар явуулж буй үйлдлүүд болон үндэснийхээ ашиг сонирхлыг хангахын тулд хилийн чанад дахь үйл явдал, нөхцөл байдалд нууцаар нөлөөлөхөөр явуулж буй операци  гэж үзэж байна.    Барууны судлаачид тагнуулын үйл ажиллагааг улс төрийн, эдийн засгийн, шинжлэх ухаан, технологийн, цэргийн, сөрөх тагнуулын, эрүүгийн зэрэг хэлбэрүүдтэй хэмээн үздэг М.Цогтоо. Тагнуулын нэр томъёоны асуудалд. УБ .

 Эшлэл 

 Нэмэлт материал 
Судалгаа
 Andrew, Christopher. For the President's Eyes Only: Secret Intelligence and the American Presidency from Washington to Bush (1996)
 Black, Ian and Morris, Benny Israel's Secret Wars: A History of Israel's Intelligence Services (1991)
 Bungert, Heike et al. eds. Secret Intelligence in the Twentieth Century (2003) essays by scholars
 Dulles, Allen W. The Craft of Intelligence: America's Legendary Spy Master on the Fundamentals of Intelligence Gathering for a Free World (2006)
 Kahn, David The Codebreakers: The Comprehensive History of Secret Communication from Ancient Times to the Internet (1996), 1200 pages
 Lerner, K. Lee and Brenda Wilmoth Lerner, eds. Encyclopedia of Espionage, Intelligence and Security (2003), 1100 pages. 850 articles, strongest on technology
 Odom, Gen. William E. Fixing Intelligence: For a More Secure America, Second Edition (Yale Nota Bene) (2004)
 O'Toole,  George. Honorable Treachery: A History of U.S. Intelligence, Espionage, Covert Action from the American Revolution to the CIA (1991)
 Owen, David. Hidden Secrets: A Complete History of Espionage and the Technology Used to Support It (2002), popular
 Richelson, Jeffery T. A Century of Spies: Intelligence in the Twentieth Century (1997)
 Richelson, Jeffery T. The U.S. Intelligence Community (4th ed. 1999)
 Shulsky, Abram N. and Schmitt, Gary J. "Silent Warfare: Understanding the World of Intelligence" (3rd ed. 2002), 285 pages
 West, Nigel. MI6: British Secret Intelligence Service Operations 1909–1945 (1983)
 West, Nigel. Secret War: The Story of SOE, Britain's Wartime Sabotage Organization (1992)
 Wohlstetter, Roberta. Pearl Harbor: Warning and Decision (1962)

Дэлхийн нэгдүгээр дайн
 Beesly, Patrick.  Room 40. (1982). Covers the breaking of German codes by RN intelligence, including the Turkish bribe, Zimmermann telegram, and failure at Jutland.
 May, Ernest (ed.) Knowing One's Enemies: Intelligence Assessment before the Two World Wars (1984)
 Tuchman, Barbara W. The Zimmermann Telegram (1966)
Yardley, Herbert O. American Black Chamber (2004)

Дэлхийн хоёрдугаар дайн 1931–1945
 Babington Smith, Constance. Air Spy: the Story of Photo Intelligence in World War II (1957) - originally published as Evidence in Camera in the UK
 Beesly, Patrick. Very Special Intelligence: the Story of the Admiralty's Operational Intelligence Centre, 1939–1945 (1977)
 Hinsley, F. H. British Intelligence in the Second World War (1996) (abridged version of multivolume official history)
 Jones, R. V. Most Secret War: British Scientific Intelligence 1939–1945 (2009)
 Kahn, David.  Hitler's Spies: German Military Intelligence in World War II (1978)
 Kahn, David.  Seizing the Enigma: the Race to Break the German U-Boat Codes, 1939–1943 (1991)
 Kitson, Simon.  The Hunt for Nazi Spies: Fighting Espionage in Vichy France, Chicago:  University of Chicago Press, (2008). ISBN 978-0-226-43893-1
 Lewin, Ronald. The American Magic: Codes, Ciphers and the Defeat of Japan (1982)	
 May, Ernest (ed.) Knowing One's Enemies: Intelligence Assessment before the Two World Wars (1984)
 Smith, Richard Harris. OSS: the Secret History of America's First Central Intelligence Agency (2005)
 Stanley, Roy M. World War II Photo Intelligence (1981)
 Stevenson, William. A Man Called Intrepid: The Incredible WWII Narrative of the Hero Whose Spy Network and Secret Diplomacy Changed the Course of History (2009)
 Wark, Wesley K. The Ultimate Enemy: British Intelligence and Nazi Germany, 1933–1939 (1985)
 Wark,  Wesley K. "Cryptographic Innocence: the Origins of Signals Intelligence in Canada in the Second World War", in: Journal of Contemporary History 22 (1987)

Хүйтэн дайн 1945–1991
 Aldrich, Richard J. The Hidden Hand: Britain, America and Cold War Secret Intelligence (2002).	
 Ambrose, Stephen E. Ike's Spies: Eisenhower and the Intelligence Establishment (1981).
 Andrew, Christopher  and Vasili Mitrokhin. The Sword and the Shield: The Mitrokhin Archive and the Secret History of the KGB (1999)
 Andrew, Christopher, and Oleg Gordievsky. KGB: The Inside Story of Its Foreign Operations from Lenin to Gorbachev (1990).
 Bogle, Lori, ed. Cold War Espionage and Spying (2001), essays by scholars
 Boiling, Graham. Secret Students on Parade: Cold War Memories of JSSL, CRAIL, PlaneTree, 2005. ISBN 1-84294-169-0
 Dorril, Stephen. MI6: Inside the Covert World of Her Majesty's Secret Intelligence Service (2000).
 Dziak,  John J. Chekisty: A History of the KGB (1988)
 Elliott, Geoffrey and Shukman, Harold. Secret Classrooms. An Untold Story of the Cold War. London, St Ermin’s Press, Revised Edition, 2003. ISBN 1-903608-13-9
 Koehler, John O. Stasi: The Untold Story of the East German Secret Police (1999)
 Ostrovsky, Viktor By Way of Deception (1990)
 Persico, Joseph. Casey: The Lives and Secrets of William J. Casey-From the OSS to the CIA (1991)
 Prados, John. Presidents' Secret Wars: CIA and Pentagon Covert Operations Since World War II (1996)  	 	
 Rositzke, Harry. The CIA's Secret Operations: Espionage, Counterespionage, and Covert Action (1988)
 Trahair, Richard C. S. Encyclopedia of Cold War Espionage, Spies and Secret Operations (2004), by an Australian scholar; contains excellent historiographical introduction
 Weinstein, Allen, and Alexander Vassiliev. The Haunted Wood: Soviet Espionage in America—The Stalin Era (1999).

 Цахим холбоос 

 Тагнуулын ерөнхий газрын цахим хуудас
 Intelligence Literature: Suggested Reading List (CIA)
 The Literature of Intelligence: A Bibliography of Materials, with Essays, Reviews, and Comments by J. Ransom Clark, Emeritus Professor of Political Science, Muskingum College
 Intelligence Online Investigative news and reporting on intelligence activities worldwide, including secret service and industrial espionage (subscription required).