| 1. |  | Erie quadrangle, Illinois : 15 minute series (topographic) | Illinois; Maps; Topographic maps; Topography; Erie (Ill.) | 1 map : col.; Relief shown by contours and spot heights.; "Topography from aerial photographs by Kelsh plotter and by plane-table surveys 1952. Aerial photographs taken 1951"; "Contour interval 10 feet."... |
