Butler, George D., 1893-1985
, National Recreation Association
and United States. Bureau of Labor Statistics.
Park Recreation Areas in the United States, 1930 : Bulletin of the United States Bureau of Labor Statistics, No. 565 ,
Washington:
U.S. Govt. Print. Off.,
May 1932, https://fraser.stlouisfed.org/title/4100,
accessed on October 9, 2024.