Correspondence, manuscripts, galley proofs, research notes, articles, interviews, course notes, photographs, printed materials, and microfilms. The correspondence begins in 1962 and ends in 1990; it details his professional work and interests. The manuscripts are extensive and are accompanied by his research notes. Prominant among the manuscripts are: "The American Nation;" "Interviews with American Historians;" "Guide to Study Abroad;" "Harper Encyclopedia of Notable Americans." In addition there are numerous subject files covering a wide range of topics and people