information on gasoline and why 93 octane doesn't mean the same in every state
MTBE, Oxygenates, and Motor Gasoline - EIA:
https://www.eia.gov/outlooks/steo/special/pdf/mtbe.pdf
EPA Gasoline Standards:
https://www.epa.gov/gasoline-standards
Reformulated gasoline (RFG):
https://www.epa.gov/gasoline-standards/reformulated-gasoline
https://nepis.epa.gov/Exe/ZyPDF.cgi/00000FG5.PDF?Dockey=00000FG5.PDF
USA Gasoline Requirements:
https://www.api.org/oil-and-natural-gas/wells-to-consumer/fuels-and-refining/fuels/us-gasoline-requirements
https://www.api.org/-/media/Files/Policy/Fuels-and-Renewables/2016-Oct-RFS/US-Fuel-Requirements/US-Gasoline-Requirements-Map.pdf