Federal Reserve Bank of Dallas. "Regulations G, T, U, and X, Circular No. 81-17," District Notices (Federal Reserve Bank of Dallas) (January 21, 1981). https://fraser.stlouisfed.org/scribd/?item_id=541198&filepath=/files/docs/historical/frbdal/circulars/frbdallas_circ_19810121_no81-017.pdf&start_page=1, accessed on October 19, 2017.
Extension of the Expiration Date of Forms, Relating to Margin Requirements on Securities Credit Transaction.