Title supplied by cataloger based on information from sheet labels. Images are photoreductions of mosaics created from original aerial photographs. Designating symbol SZ; form of individual image numbering: SZ-1-[number], SZ-2-[number], SZ-3-[number], SZ-4-[number], SZ-5-[number], or SZ-6-[number]."Date of completion 09-19-37" Flown by Gatschet Aerial Surveys, Des Moines, Iowa. Library's copy 2 on sheets 36 x 29 cm. or smaller."Approximate scale, 1:20,000" [refers to individual images from which mosaic was made]. Contact the Map Collection at The University of Iowa Libraries: http://www.lib.uiowa.edu/maps/contact/