| Answer | Crossword Clue |
|---|---|
| PLANEGEOMETRY | Subject of a Euclidean treatise |
| OPTICS | Subject of a Helmholtz treatise. |
| WHIST | Subject of a Hoyle treatise |
| tractate | a formal, systematic, written account of a subject, also TREATISE |
| tractates | TRACTATE, a formal, systematic, written account of a subject, also TREATISE |
| treatises | TREATISE, a formal, systematic, written account of a subject, also TRACTATE |
| monograph | a special treatise on a particular subject of limited range / to write a monograph |
| ground | to make a certain amount of progress in dealing with a piece of work, subject, treatise, or the like |
