Sproul, Allan, 1896-1978. Letter, Allan Sproul to O. S. Powell, . https://fraser.stlouisfed.org/archival/1174/item/3401, accessed on May 2, 2024.
Sproul, Allan, 1896-1978. Letter, Allan Sproul to O. S. Powell, . https://fraser.stlouisfed.org/archival/1174/item/3401, accessed on May 2, 2024.