| Answer | Crossword Clue |
|---|---|
| APP | Book supplement: Abbr. |
| ADD | Book supplement: Abbr. |
| ADDENDUM | Supplement to a book |
| ADDENDUM | Supplement to a book. |
| append | add as a supplement or appendix (as in a book) |
| addendum | supplement to a book often used in plural but singular in construction |
