Federal Reserve Bank of Dallas. "The Introduction of a Post Office Box Service for Savings Bond Transactions, with Instructions for Processing Both Series HH Exchange Applications and Treasury Form PD 2639, Circular No. 86-37,"
District Notices (Federal Reserve Bank of Dallas)
(April 18, 1986).
https://fraser.stlouisfed.org/title/5569/item/545501, accessed on May 20, 2025.