Incoming Resources
- Results of spirit leveling in Illinois, 1896 to 1908, inclusive, compiled by S.S. Gannett and D.H. Baldwin ; in cooperation with the Illinois State Geological Survey during 1905 to 1908, inclusive
- Spirit leveling in Illinois, 1896-1942, prepared in cooperation with the State of Illinois, Department of Registration and Education, Geological Survey Division
- Spirit leveling in Illinois, 1914 to 1917, inclusive, R. B. Marshall