I'm uncertain which article to use in the following examples:
- calotype, invented by an/the Englishman William Henry Fox Talbot
- paper, written by a/the Scottish professor John Dudgeon
- a studio founded by an/the American George R. West
- In 1859, a/the Swiss photographer Pierre Joseph Rossier (c.1829-1897) took the first photo....
Seeing as Scottish and Swiss work as adjectives, but Englishman is a noun, is there a preference for using one article over another?