|Class E - States of the United States||Iowa|
|Works related to Iowa, a state of the United States.|
- "The Great Iowa Meteor", by Gustavus Detlef Hinrichs in Popular Science Monthly Volume 7, September 1875
- History of Iowa From the Earliest Times to the Beginning of the Twentieth Century (1903)
- “Iowa” by Eaton S. Drone in The American Cyclopædia, 1879
- “Iowa” by Henry Gannett in Encyclopædia Britannica (9th ed.), 1881.
- “Iowa” in The Nuttall Encyclopædia by James Wood, London: Frederick Warne and Co., Ltd., 1907.
- “Iowa” in Encyclopædia Britannica, (11th ed.), 1911
- “Iowa,” by John I. Mullany in Catholic Encyclopedia, 1913.
- “Iowa,” Collier's New Encyclopedia. New York: P.F. Collier & Son Co., 1921.
- John Carl Parish, “Iowa,” Encyclopædia Britannica (12th ed.), 1922.