- Fact Sheet: EPA Issues a Direct Final Rule to Modify Certain Provisions of the Reformulated and Conventional Gasoline Regulations Including Provisions for Butane Blenders and Attest Engagements (PDF) (5 pp, 228 K, EPA420-F-05-030, December 2005)
- Direct Final Rule (PDF) (29 pp, 233 K, published December 15, 2005)
- Butane Blending Technical Analysis (PDF)(8 pp, 140 K, 4/28/03)