Title supplied by cataloger based on information from sheet labels. Images are photoreductions of mosaics created from original aerial photographs. Designating symbol BZV. Form of individual image numbering: BZV-1-[number], BZV-2-[number], BZV-3-[number], or BZV-4-[number]. "Date of completion July 26, 1939." Flown by Aero Service Corp. Philidelphia, Pa. "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/