See biography by W. D. Foulke (1899, repr. 1974); W. B. Hesseltine, Lincoln and the War Governors (1948).
Oliver Perry Hay (22 May, 1846 – 2 November, 1930) was an American professor and paleontologist. In 1912, Hay was appointed as a research associate at the Carnegie Institute, and was given office space at the United States National Museum. There he did much work with the USNM's collections in vertebrate paleontology. He published extensively on fossil turtles and Pleistocene mammals. The catalogs that he constructed were a great aid in recording existing knowledge and became standard references. His papers from 1911 to 1930 are stored at the Smithsonian Institution.