11. Standard historical atlas of Plymouth County, Iowa, 1907 Maps University Of Iowa Public content 1907. Material in the public domain. No restrictions on use. University of Iowa. Libraries. Map Collection. Anderson & Goodwin Co.
12. The LeMars semi-weekly sentinel sectional pocket map of Plymouth County, Iowa, with comprehensive statistics, 1891 Maps University Of Iowa Public content 1890. Ragsdale & Chassell (Firm). 1 map. Ragsdale & Chassell.