Karl S. Twitchell was an American mining engineer who conducted extensive surveys in the Middle East, Europe, and South America between 1915 and the 1950s. His papers document the span of his career, particularly his interest in the Middle East, and include correspondence, journals, notes, reports, writings, topical files, photographs, and maps. Personal documents and correspondence with family and associates are also contained.

Consists of personal papers of Kaiē Tsitselē, Greek author and translator, who contributed to the dissemination of the Modern Greek literature outside Greece. The collection consists of manuscripts of some of Tsitselē's novels, short stories, radio scripts, and book reviews along with her English translations of Greek works. Correspondence with her friends and colleagues completes the collection.

Contains over 3000 manuscripts relating to the Rossetti's and their friends. While Dante Gabriel is the central figure, his brother and sisters (William Michael, Christina Georgina, Maria Francesca) are also represented, as are several other members of the Polidori/Rossetti families. The material in the collection was acquired by Janet (Camp) Troxell between 1930 and 1965.

Consists of letters to Gilbert Troxell from Sinclair Lewis, John O'Hara, and Carlotta Monterey O'Neill, the wife of Eugene O'Neill, discussing the donation of manuscripts to the Sterling Memorial Library at Yale University.

William C. Trimble, Princeton University Class of 1930, was a career diplomat, serving as United States ambassador to Cambodia (1959-1962) and Deputy Assistant Secretary of State for African Affairs (1965-1968) as well as serving in Brazil and Germany. The collection contains correspondence, speeches, newspaper clippings, photographs, and assorted memorabilia documenting Trimble's career.

Consists of approximately 100 letters and postcards addressed to Trigueiros from seven correspondents: Jorge Amado (1967-1995), António S. Celestino (1973), Manuel Ferriera (1959-1966), Jesué Pinharanda Gomes (1960-1995), António Guedes de Amorim (1947-1971), Afonso Lopes Vieira (1935-1944), and José Rodrigues Júnior (1958-1987).

Ridgely Torrence was an American poet, playwright, and editor of The New Republic, and his papers document the literary activity and relationship of a large group of American writers between the years 1890 and 1950. Particularly well-represented are American poets William Vaughn Moody and Edwin Arlington Robinson.