| #291 | Octane week. -- Arlington : Hart Fuels Information Services. -- ISSN 1072-8740 |
| #292 | Oesterreichische Zeitschrift fuer Elektrizitaetswirtschaft. -- Wien : Springer. -- ISSN 0029-9618 |
| #293 | Oesterreichs Energie : Fachmagazin der österreichischen E-Wirtschaft. -- Wien : Österreichischer Wirtschaftsverlag, 2010- |
| #294 | Offshore. -- Conroe : Industrial Publications. -- ISSN 0030-0608 |
| #295 | Oil and gas investor this week. -- Houston : Hart Energy Publishing, 1992-. -- ISSN 1940-5189 print. -- ISSN 1940-5197 online |
| #296 | Oil and gas investor's A & D watch. -- Potomac : Hart Energy Publications, 2001-. -- ISSN 1940-8471 print. -- ISSN 1940-848X online |
| #297 | Oil & gas interests newsletter. -- Houston : Tamarack Consulting, 1986-. -- ISSN 1073-0265 |
| #298 | Oil & gas investor. -- Denver : Investor Pub. Co., 1981-. -- ISSN 0744-5881 |
| #299 | Oil & gas journal. -- Tulsa : PennWell, 1910-. -- ISSN 0030-1388 print. -- ISSN 1944-9151 online |
| #300 | Oil, gas & petrochem equipment. -- Tulsa : Petroleum Pub. Co., 1969-. -- ISSN 0030-1353 |