Atlas of Clay County. Watertown, SD: Centennial Atlas, c1990. Locations: Main Collection and Chilson Collection, G1448 .C53 A84 1990. This set includes atlases of many other SD counties.
Briggs, Harold Edward. “The early history of Clay County.” Master’s Thesis, University of South Dakota, 1924. Locations: USD Theses & Dissertations and USD Archives, LD5071.3x .B76863. Also in South Dakota Historical Collections volume 13, page 69-157. Time period covered is 1804 to 1888. No photographs.
Carlberg, Janet Joyce. “A study of place-names in Clay County, South Dakota.” Master’s Thesis, University of South Dakota, 1962. Location: USD Theses & Dissertations, LD 5071.3x .C1918.
Carlsen, Nancy L. Clay County Historic Preservation Commission cemetery inventory. Vermillion, SD: Clay County Historic Preservation Commission, 2008. Location: Vermillion Public Library South Dakota Reference, LMC 929.5 .C284.
Census of 1860. South Dakota Historical Collections volume X, 1920. Locations: Main Collection and Chilson Collection, F646 .S76. Includes a section on Vermillion and Clay County.
Clay County, SD air photos. Brookings, SD: Plant Science Dept., SD Agricultural Experiment Station, South Dakota State University, [2003]. Location: Storage - Gov Docs, ED 175:P 324. This set includes photographs of many other SD counties.
Guide to National Register of Historic Places in Clay County, South Dakota. Vermillion, SD: Clay County Historic Preservation Commission, 2007. Locations: Main Collection and Chilson Collection, F657 .C6 G852 2007.
Kryger, Marion L. Homesteaders of Clay County, South Dakota: reference guide for 1884 map of Clay County. Vermillion, SD: M. Kryger, 1999. Locations: Main Collection and Chilson Collection, F657 .C6 K79 1999.
Moore, Charles S. Pocket atlas of Clay County, South Dakota. Vermillion, SD: Dakota Republican (printer), 1894. Location: Chilson Collection, CC2024.01.
Moses, Lloyd R. Clay County place names. Vermillion, SD: Clay County Historical Society, 1976. Locations: Main Collection and Chilson Collection, F657 .C6 C55 1976.
Ogle, George A. Standard atlas of Clay County, South Dakota. Chicago: Geo. A. Ogle & Co, 1912. Locations: Atlas Collection and Chilson Collection, G4183 .C5 1912.
Ogle, George A. & Company. Memorial and Biographical Record of Turner, Lincoln, Union and Clay Counties, South Dakota. Containing Biographical Sketches of Hundreds of Prominent Old Settlers and Representative Citizens, with a Review of Their Life Work; Their Identity with the Growth and Development of These Counties; Reminiscences of Personal History and Pioneer Life; and Other Interesting and Valuable Matter Which Should Be Preserved in History. Chicago: G. A. Ogle &, 1897. Locations: Circulating Reference and Chilson Collection, F650 .M52x.
Parker, Donald Dean. History of our county and state [Clay County]. Brookings, SD: South Dakota State College, [1959]. Locations: Main Collection and Chilson Collection, F657 .C6 P32x.
Peterson, August. “Clay County indicating the area of about 37,500 acres and the names of 236 Swedish pioneers who made their settlement and obtained patents from U.S.” [S.l: s.n.], 1900. Location: Chilson Collection, Map 4183 .C5 E27 1914.
Peterson, August. History of the Swedes who settled in Clay County, South Dakota, and their biographies. Clay County, SD: The Swedish pioneer and historical society of Clay County, SD, 1947. Locations: Main Collection and Chilson Collection, F657 .C6 P48x.
Schell, Herbert S. Clay County: chapters out of the past. Vermillion, SD: Vermillion Area Chamber of Commerce, 1985. Locations: Main Collection and Chilson Collection, F657 .C6 S36. Includes chapters on first decade, Black Hills, Missouri River, great Dakota boom, farming, livestock, flour mill and creamery, brickmaking and early manufacturing, newspapers, medical practice, schools, university, athletics, civic improvements, fires, churches, temperance, Chautauqua, and water problem.
Schell, Herbert S. History of Clay County, South Dakota. Vermillion, SD: Clay County Historical Society, 1976. Locations: Main Collection and Chilson Collection, F657.C6 S34x. Time period covered is 1500 to 1976. Includes photographs. Contains index.
Smith, Elizabeth T. Historic Vermillion and Clay County. Chicago: Arcadia Publishing, 2002. Locations: Main Collection and Chilson Collection, F659 .V4 S64 2002.
South Dakota State Planning Board and Clay County Planning Board. Economic and social survey of Clay County. Brookings, SD: Works Progress Administration Sponsored Federal Project No. #3, 1936. Location: South Dakota Documents, EX 650:P694/Su 79/C 579.
Vermillion Plain Talk. “Historical sketches of Vermillion and Clay County, commemorating Vermillion’s one hundredth anniversary”. Vermillion Plain Talk. An article appeared in each weekly issue from February 5th through August 1959. Location: Chilson Collection.