| Answer | Crossword Clue |
|---|---|
| OED | It took 70 years to complete, in brief |
| OED | Ref. work that took 70 years to complete |
| OED | Ref. work that took more than 70 years to complete |
| OED | Publication whose first ed. took more than 70 years to complete |
| FERMAT | It took 358 years to prove his "last theorem" |
