| #301 | Oil Shale. -- Tallinn : Estonian Academy Publishers, 1984-. -- ISSN 0208-189X print. -- ISSN 1736-7492 online |
| #302 | Oilweek. -- Calgary : Maclean-Hunter, 1958-1995. -- ISSN 0030-1515 |
| #303 | Ökoenergie : Magazin zur Főrderung erneuerbarer Energie und der Energieeffizienz. -- Wien : Ökosoziales Forum Österreich |
| #304 | Oman oil & gas report. -- London : Business Monitor International, 2005-. -- ISSN 1748-4138 |
| #305 | Operating engineer : operation and maintenance of the power services. -- Spojené státy americké : New York : McGraw-Hill, 1947-1951 |
| #306 | Oxy - fuel news. -- Washington : Hart Fuels Information Services. -- ISSN 1072-8759 |
| #307 | Pacific and Asian Journal of Energy. -- New Delhi : Tata Mc Graw-Hill Publishing Company Limited, 1987-. -- ISSN 0970-3888 |
| #308 | Pakistan oil & gas report. -- London : Business Monitor International, 2007-. -- ISSN 1748-4146 |
| #309 | Pakistan power report. -- London : Business Monitor International, 2007-. -- ISSN 1754-4033 |
| #310 | Paliva : odborný časopis pro plynárenství, koksárenství a úpravnictví. -- Praha : St.nakl.techn.lit., 1950-1966. -- ISSN 0369-8262 |