United States. Bureau of the Census. "Comparisons from Specific Peak and Trough Levels and Specific Trough Dates," in United States. Bureau of the Census. "March 1965," Business Conditions Digest (March 1965) : 68-68. https://fraser.stlouisfed.org/title/43/item/7213/toc/300757 , accessed on March 28, 2024.