Professional and personal files including Armstrong's correspondence with professional associations, other engineers, and friends, his research notes, circuit diagrams, lectures, articles, legal papers, and other related materials. Of his many inventions and developments, the most important are: 1) the regenerative or feedback circuit, 1912, the first amplified radio reception, 2) the superheterodyne circuit, 1918, the basis of modern radio and radar, 3) superregeneration, 1922, a very simple, high-power receiver now used in emergency mobile service, and 4) frequency modulation - FM, 1933, static-free radio reception of high fidelity. More than half the files concern his many lawsuits, primarily with Radio Corporation of America, over infringement of the Armstrong patents. Litigation continued until 1967. Other files deal with his work in the Marcellus Hartley Research Laboratory at Columbia University, 1913-1935, and with the American Expeditionary Forces in France during World War I, his Air Force contracts for communications development, Army research during World War II, the Radio Club of America, the Institute of Radio Engineers, FM development at his radio station at Alpine, N.J., the use of FM in television, his involvement in Federal Communications Commission hearings and legislation, and his work with the Zenith Radio Corporation. Also, letters to H.J. Round

The collection includes more than 100 letters to Benningsen from P.P. Ignatév, the last Minister of Imperial Russia, written in 1920-1921; and correspondence between Benningsen and his wife, Ekaterina Platonovna Benningsen, and Ksenii︠a︡ V. Denikina. Several manuscripts by E. P. Benningsen are also included: a long memoir which treats the history of the Benningsen family, his own government and Red Cross service, the 1917 Revolution and the Civil War, and emigration in France and Brazil. There are copies of his lectures and articles on historical topics; a lengthy essay on the character of modern politics called "Ce que la vie m'a enseigne"̀; and a number of reviews of books dealing with Russia. There are two sets of subject files: one containing materials relating to the activities of the "Soi︠u︡z Pazheĭ" (an emigre organization of former members of the Corps of Pages); the other, materials relating to the efforts by former officers of the Kavalergardskiĭ Regiment to recover a trove of silver objects belonging to them that they had deposited in the State Treasury at the beginning of World War I and which finally ended up in Belgrade. A brief biographical note on her husband by Ekaterina P. Benningsen and a few photographs complete the collection.

Correspondence, scripts, manuscripts, and reports regarding his activities in the American radio and film industries. Included are papers regarding projects for the United State Government, the Indian film industry, various television and radio networks, and private ventures. Also included is material regarding the Center for Mass Communications of Columbia University, in which Barnouw figured prominently and files for the books he has written.

Correspondence, manuscripts, memorabilia, photographs, and printed materials. The correspondence consists of letters relating to the publication and review of Jäckh's books, articles, and book reviews and typescript copies of letters by Hans Jäckh. There are manuscripts for his articles, lectures and speeches as well as clipping files of book reviews and articles by and about Jäckh in the European and North American press. The bulk of the collection is written and printed in German and deals with the Balkans and the Near East before 1920, including the Balkan War of 1912-1914, and the Turkish Revolution. Of particular interest are manuscripts and articles describing his land travels between 1903 and 1913 with the German fleet and on hot air balloons. Other topics covered include the Hocjschule für Politik, German labor unions, German-European relations, European attitudes towards the United States, and his literary works. There are also some manuscripts dealing with the Balkans and the Near East during World War II. An extensive file of photographs depicts, Albania, Asia Minor, Baghdad, the Balkans, Constantinople, Genoa, the German naval fleet, the Hochschule für Politik, hot air balloons, Italy, the Mediterranean, Turkey, the Turkish Revolution, the United States, Versailles, and Weimar. There are books from Jäckh's library, some with marginal notes, some signed and inscribed to him as well as copies of his own works.

Correspondence, manuscripts, notes, drafts of speeches, appointment books, subject files, documents, photographs, memorabilia and printed materials. There are notes from her lectures on Sociology at Adelphi College in 1911-1912; papers from 1912-1932, when Perkins served on the Commission for Safety and on the Industrial Commission of New York State; the main body of the material is from the period of her cabinet office, 1933-1945; and some items from her days on the Civil Service Commission, 1946-1953. Also included are personal and family papers.

Manuscripts of essays and course notes taken while a student at Amherst College, 1884-1889, and at Berlin University, 1892-1894. Articles, addresses, essays, lectures, lecture notes and reading notes. Also included are diaries for the years 1936-1940 and correspondence concerning Amherst College, Columbia University, and Woodbridge's stay as a visiting scholar in Berlin, 1931-1932. Among his correspondents are: Frederick S. Allis, Secretary of the Amherst Board of Trustees; Stanley King, President of Amherst; and Nicholas Murray Butler, President of Columbia. Some photographs are also included.

Personal and professional correspondence, publications, poetry manuscripts and diaries, and scrapbooks belonging to Prudential Insurance Company statistician, cancer researcher, and eugenicist Frederick Ludwig Hoffman (1865-1946). These items document Hoffman's career, family life, and his extensive travels.

Personal and professional papers of the notable literary critic. The collection includes correspondence, manuscripts, notes, journals, photographs, drawings and films, and a collection of signed and annotated books and magazines from Dupee's library.

The papers include correspondence, manuscripts, notes, and printed materials. Among the correspondents are Sergeĭ Bulgakov, Nikolaĭ Losskiĭ, and Marina T︠S︡vetaeva, and there are one or two letters each from Nina Berberova, Georgiĭ Florovskiĭ, and Semen Frank. There is substantial family correspondence, primarily letters from Fedotov to his wife and daughter. Manuscripts include articles and lectures by Fedotov, and a draft of his translation of the Book of Psalms into Russian; there is also a poem by Marina T︠S︡vetaeva, "M.V." (1932). Printed material consists of off-prints of many of Fedotov's articles. There are subject files on Nikolaĭ Berdi︠a︡ev and on the Bogoslovskiĭ Institute conflict in the late 1930s.

Correspondence, manuscripts, notes, notebooks, documents, photographs, course-related materials, and printed materials. The manuscripts include typescripts of Sykes' published and unpublished novels, monographs, plays, short stories, and articles. Among these are The Perennial Avant Garde, The Cool Millennium, and The Hidden Remnant. Sykes' notes and notebooks span the period from the early 1930s to 1980, and include preliminary ideas and sketches for his books, as well as autobiographical material. A small number of documents concern Sykes' wartime work in the U.S. Government Office of War Information. Course-related material including writings and correspondence of students taught by Sykes between 1962 and 1975 at the New School and as an adjunct professor at Columbia University. Printed materials consist of numerous reviews of Sykes' books, in addition to offprints and articles by Sykes. Included as well are printed materials about or connected with Sykes, offprints of articles inscribed to him, and many volumes from his library. The substantial correspondence series includes personal letters and correspondence with agents and publishers relating to his books. Correspondents include Harold Clurman, Aaron Copland, Lawrence Durrell, Georgia O'Keeffe, and Francis Steegmuller, as well as a number of Sykes' students. There is extensive correspondence between Sykes and the artist John Hartell from 1927 to 1983.