Andrew R. L. Cayton, ed (2006). “Small-town life”. The American Midwest: An Interpretive Encyclopedia. Richard Sisson, Chris Zacher. Bloomington, Indiana: Indiana University Press. pp. 1119–1120. ISBN978-0-253-34886-9. https://books.google.co.jp/books?id=n3Xn7jMx1RYC&pg=PA1119&redir_esc=y&hl=ja. "The universal embrace of the automobile in the 1920s contributed to the sharp decline of Main Street's independence and vitality ... The ensuing Great Depression ruthlessly exposed the vulnerability of small-town merchants ... The causes of decline are many and complex, but they are related to the continued accumulation of population, economic strength, political power, and social dominance by regional cities."
Williamson, Samuel H. (April 2010). Seven Ways to Compute the Relative Value of a U.S. Dollar Amount, 1774 to present. MeasuringWorth. Calculations made using Nominal GDP Per Capita, a measure of capital intensivity, using "the 'average' per-person output of the economy in the prices of the current year." This is a measure of the amount of capital and volume of labor required to reproduce the work over varying production methods, but assuming that money represents a proportion of the economy.
“2009 County Level Data (Indiana)”. United States Department of Agriculture's National Agricultural Statistics Service. 2010年9月19日閲覧。
nrcs.usda.gov
Soil Survey of Warren County, Indiana(PDF) (Report). United States Department of Agriculture's Soil Conservation Service. 1990. 1991-281-364/20052. 2010年12月24日閲覧。
