Federal Reserve Bank of Dallas. "Amendment to Regulation T, Circular No. 81-201," District Notices (Federal Reserve Bank of Dallas) (October 22, 1981). https://fraser.stlouisfed.org/scribd/?item_id=541383&filepath=/files/docs/historical/frbdal/circulars/frbdallas_circ_19811022_no81-201.pdf&start_page=1, accessed on September 25, 2017.
Regulation T, Credit by Brokers and Dealers. Amended Effective 10-26-81, to Establish Margin Requirement for Options on Exempted Debt Securities.