Columbia subject headings:
Petroleum industry and trade--Government ownership--Mexico.
Petroleum industry and trade--Mexico.
Petróleos Mexicanos.
Harvard subject headings:
Petroleum industry and trade--Government ownership--Mexico
Petroleum industry and trade--Mexico
Petróleos Mexicanos
Princeton subject headings:
Petroleum industry and trade--Government ownership--Mexico.
Petroleum industry and trade--Mexico.
Petróleos Mexicanos.