United States. Bureau of Economic Analysis. "Non-SMSA Portions of BEA Economic Areas, Volume 6" in 1972 OBERS Projections : Regional Economic Activity in the United States; By Economic Area, Water Resources Region and Subarea, State, and SMSA and Non-SMSA Portions of the Areas, Historical and Projected, 1929-2020 (April 1974). https://fraser.stlouisfed.org/title/9208/item/682145, accessed on July 16, 2025.