| Clue | Source | Date |
|---|---|---|
| Some fracking byproducts | LA Times Daily | 20 May 2023 |
| Fuel gases | Premier Sunday | 23 Apr 2023 |
| Odorless fuels | ||
| Molecules in natural gas | ||
| Some fuel gases | ||
| Natural gas components | ||
| Some soil contaminants | ||
| Fuel gases | ||
| Some fuels | ||
| Natural gases | ||
| Some fuel gases | ||
| Natural-gas components | ||
| Hydrocarbons. | ||
| Compounds occurring in natural gas. |