The following information is taken from the Dictionary of the Older Scottish Tongue, available online at http://www.dsl.ac.uk/index.html. This is a work in progress.
| Spelling | Number | Dates & headers |
|---|---|---|
| Fergisoune | 3 | 1645 (cognosce, corn, cut) |
| Fergusson | 2 | 1495 (chaplan, college kirk) |
| Ferguson | 1 | 1581 (braggand) |
| Fergusoun | 1 | 1605 (crame) |
| Fergussoune | 1 | 1582 (bowar) |