| Cartel based in Vienna | 22 |
| Crude cartel | 12 |
| Barrel bunch, briefly | 21 |
| Cartel acronym | 14 |
| Oil cartel acronym | 18 |
| Oil cartel letters | 18 |
| Oil-cartel acronym | 18 |
| Crude group | 11 |
| Oil org. | 8 |
| Crude group? | 12 |
| Vienna-based cartel | 19 |
| Crude bunch? | 12 |
| Cartel since 1960 | 17 |
| Arab oil org. | 13 |
| Oil gp. | 7 |
| Crude org. | 10 |
| Cartel letters | 14 |
| Vienna-based org. | 17 |
| Trade org. since 1960 | 21 |
| Oil grp. | 8 |
| Intl. oil group | 15 |
| Acronym for an oil-rich group | 29 |
| "Black gold" bloc | 27 |
| Oil cartel initials | 19 |
| Fuel cartel acronym | 19 |
| Fuel cartel | 11 |
| Crude grp. | 10 |
| Cartel since 1960, briefly | 26 |
| Cartel formed in 1960 | 21 |
| Cartel formed in '60 | 24 |
| Acronym since 1960 | 18 |
| "Well"-financed grp. | 30 |
| "Black gold" grp. | 27 |
| Well-known cartel? | 18 |
| Well-financed gp.? | 18 |
| Petroleum gp. | 13 |
| Oil-cartel letters | 18 |
| Oil ministers' org. | 23 |
| Intl. cartel | 12 |
| Grp. that has energy users over a barrel? | 41 |
| Grp. affecting gas prices | 25 |
| Energy cartel | 13 |
| Crude letters | 13 |
| Crude grp.? | 11 |
| Crude acronym | 13 |
| Cartel that added Angola in 2007 | 32 |
| Cartel est. in 1960 | 19 |
| Bloc with barrels, briefly | 26 |
| Barrel-producing gp. | 20 |
| Worldwide oil power | 19 |
| Vienna-based trade bloc | 23 |
| Trade org. with Saudi Arabia and Iran | 37 |
| The U.A.E. belongs to it | 24 |
| Qatar's org. | 16 |
| Powerful initials | 17 |
| Powerful energy-market gp. | 26 |
| Petroleum org. | 14 |
| Org. since 1960 | 15 |
| Org. based in Vienna | 20 |
| Oily oligopoly | 14 |
| Oily gp. | 8 |
| Oily acronym | 12 |
| Oil-producers' org. | 23 |
| Oil pricing gp. | 15 |
| Oil group | 9 |
| Oil exportation grp. | 20 |
| Oil cartel, for short | 21 |
| Oil cartel since 1960 | 21 |
| Mideast acronym | 15 |
| Kind of minister | 16 |
| Grp. with crude intentions? | 27 |
| Grp. that rolls out the barrels? | 32 |
| Grp. full of gas | 16 |
| Group whose O doesn't stand for "oil" | 51 |
| Gp. that includes Venezuela | 27 |
| Fuel cartel's letters | 25 |
| Ecuador and Venezuela are in it | 31 |
| Crude letters? | 14 |
| Crude gp. | 9 |
| Crude cartel? | 13 |
| Cartel that includes Iraq and Venezuela | 39 |
| Cartel in the news | 18 |
| Big oil cartel (abbr.) | 22 |
| Barrel org. | 11 |
| Assn. with many Gulf members | 28 |
| Angola joined it in '07 | 27 |
| Acronym for an oil-rich grp. | 28 |
| 1973 embargo org. | 17 |
| "Black gold" gp. | 26 |
| Yamani's org. | 17 |
| Worldwide oil powers | 20 |
| World oil assn. | 15 |
| What group founded in 1960 currently has 12 members? | 52 |
| Well-running group?: Abbr. | 26 |
| Well-oiled grp. | 15 |
| Well-funded grp.? | 17 |
| Well-financed grp.? | 19 |
| Vienna-based grp. with no European members | 42 |
| Vienna-based commercial gp. | 27 |
| Vienna-based bloc | 17 |